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5.a. Request by US Home Corp. PP 17th Addition
EXECUTIVE SUMMARY Planning Commission Meeting: February 26, 2019 Tentative City Council Meeting: March 19, 2019 AGENDA ITEM: Request by U.S. Home Corporation for Approval of a Planned Unit Development Master Development Plan with Rezoning, a Preliminary Plat, and a Final Plat for Prestwick Place 17th Addition. AGENDA SECTION: Public Hearing PREPARED BY: Anthony Nemcek, Planner AGENDA NO. 5.a. ATTACHMENTS: Site Location Map; Final Plat; Preliminary Plat; Existing Conditions; Grading and Erosion Plan; Utility Plan; Landscape Plan; Building Floor Plans and Elevations; City Engineer’s Memo Dated February 26, 2019 and Stormwater Review; Parks Director’s Memo Dated February 21, 2019 APPROVED BY: KL RECOMMENDED ACTION: 1. Motion to recommend the City Council approve the Preliminary Plat for Prestwick Place 17th Addition, subject to the following conditions: a. Approval of a Planned Unit Development Master Development Plan rezoning the subject property. b. The applicant shall install sidewalk on the northeastern side of Addison Avenue to connect to the existing sidewalk stub at the northern property line. c. A street lighting plan shall be submitted for review and approval prior to issuance of a building permit. d. The applicant shall appropriately sign the intersection of Street 1 and Addison Avenue as “No Left Turn”, and the end of Street 1 shall be signed “No Parking” prior to issuance of a Certificate of Occupancy. e. Street 2 alignment shall be adjusted to intersect with Addison Avenue at a 90- degree angle and attempt to eliminate short tangents/curves. f. Applicant shall update the landscape plan to relocate a tree from atop storm water infrastructure. g. Conformance with all requirements of the City Engineer as detailed in the attached memorandum dated February 26, 2019. h. Conformance with all requirements of the Parks and Recreation Director as detailed in the attached memorandum dated February 21, 2019 i. The applicant shall dedicate Outlot H to the City. j. Drainage and utility easements shall be dedicated over all ponding. k. Payment of $529.97 for AUAR study. 2 2. Motion to recommend the City Council approve the Planned Unit Development Master Development Plan with the Rezoning of the Property from AG – Agriculture to R3 PUD – Medium Density Residential Planned Unit Development and Site and Building Plan approval, subject to the following conditions: a. A deviation from Section 11-4-8 F. R-3 Minimum Lot Requirements and Standards reducing the setback from the public street from 30 feet to 25 feet and increasing the setback from property lines from 20 feet to 30 feet. b. A deviation from Section 11-2-8 A. Single Family Attached Dwellings and Townhome Requirements and Standards increasing the maximum number of units per building from 6 to 12. c. Conformance with all requirements of the City Engineer as detailed in the attached memorandum dated February 26, 2019. d. Conformance with all requirements of the Parks and Recreation Director as detailed in the attached memorandum dated February 21, 2019. 3. Motion to recommend the City Council approve the Final Plat for Prestwick Place 17th Addition, subject to the following conditions: a. Approval and execution of a subdivision agreement. b. Conformance with all requirements of the City Engineer as detailed in the attached memorandum dated February 26, 2019. c. Conformance with all requirements of the Parks and Recreation Director as detailed in the attached memorandum dated February 21, 2019 d. Payment of $74,100 for fee-in-lieu of park dedication. e. Applicant shall provide a landscaping surety in the amount $17,820. SUMMARY The Planning Commission is being asked to consider a request from U.S. Home Corporation (Lennar) for approval of a Planned Unit Development Master Development Plan with Rezoning as well as Preliminary and Final Plats to construct a 50-unit townhouse development. This site was not included in the Prestwick Place PUD that was approved in 2007, but the development standards being requested by the applicant are consistent with those approved for other medium density development projects within the Prestwick Place PUD. Those standards include an increase to the maximum number of units permitted in a single building, a reduction in the setback from a local street, and an increase in the setback from side and rear property lines. Development of the site will take place in two phases. Staff is recommending approval of this request. Owners: Arcon-Pemton, LLC. Residential Developers: Lennar Corporation Preliminary Plat Area: 7.91 Acres Met Council Net Area: 7.91 Acres Residential Lots Created: 50 Attached lots Gross Density: 6.3211 Units/Acre Net Density: 6.3211 Units/Acre Comprehensive Plan Guiding: MDR-Medium Density Residential Current Zoning: AG-Agriculture Requested Zoning: R3 PUD-Medium Density Residential Planned Unit Development Surrounding Land Uses 3 North: LDR Low Density Residential East: Agriculture West: MDR Medium Density Residential South: Designated MDR Medium Density Residential-currently vacant BACKGROUND The subject property is separate from, but adjacent to, a larger 290 acre mixed use development approved by the City in 2007 on the northwest and northeast corners of County Road 42 and Akron Avenue. The site was platted as an outlot of the larger Prestwick Place Planned Unit Development. The deviations from the Zoning Ordinance being requested by the applicant are consistent with the standards for medium density residential development neighborhood originally part of the 2007 Prestwick Place Planned Unit Development. These medium density neighborhoods included the property to the south, and some properties west of Akron Avenue which has since been reguided and developed as single family. With this development, Addison Avenue will be extended to the eastern boundary of the site. ISSUE ANALYSIS Legal Authority Preliminary plats are quasi-judicial decisions for the Planning Commission meaning that the Planning Commission is acting as a judge to determine if the regulations within the Comprehensive Plan, Zoning Ordinance, and Subdivision ordinance are being followed. The Planned Unit Development Master Development Plan is a rezoning activity and therefore is a legislative decision. Legislative decisions give the Planning Commission more latitude, but consideration should be given to the ordinance criteria for granting of PUDs and the PUD standards of other developments that have been approved in the vicinity. The recommended standards are similar to the Prestwick Place PUD standards for Single Family Attached housing. Land Use and Zoning The site under consideration is guided for medium density residential in the City’s Comprehensive Plan, which guides land for residential development at a density of 6-12 units per acre. The proposed project falls within the low end of this range at 6.32 units per acre. The applicant is requesting a rezoning to R3- PUD, medium density residential planned unit development, consistent with the site’s land use designation. Single-family attached residential units are a permitted use in the R3 district in accordance with the minimum lot requirements and setbacks specified in the Zoning Ordinance. With the PUD designation, the development must adhere to the standards, requirements, and any flexibility being proposed within the master development plan being reviewed in this report. Alternative Urban Area -wide Review The subject property falls within the CSAH 42/Akron AUAR that was adopted in 2007, updated most recently in 2017. An AUAR is an environmental review document that anticipates development over a larger area. The benefit is that an environmental review is not required for each development within the AUAR boundaries. The proposed development is located in an area anticipated to develop as medium density residential at a density of five to ten units per acre. Property owners within the AUAR boundaries must reimburse the City for the AUAR either at the time the AUAR is adopted or when the property is developed. The current owners of the property had opted to defer payment for the AUAR until development. The amount due is $529.97 ($67 per acre x 7.91 acres). General Subdivision Design The area to be developed is approximately eight acres in size, and it is located 500 feet east of Akron 4 Avenue and immediately south of the Greystone subdivisions. The townhomes will be side-by-side style. Access to the site is provided by Addison Avenue as it travels south from 141st Street East and curves east, south of the site. The site itself is bisected by a pipeline easement, and development will take place in phases that accommodate the pipeline. The first phase of development will occur on the western portion of the site, and the second phase will occur on the portion of the site east of the pipeline. Each phase will have two access points along Addison Avenue. Traffic will circulate within each phase on private roadways. The necessary amount of additional guest parking will be provided for each phase of development as it occurs. Stormwater ponding will be located within 1.29 acres in the northeast corner of the site in its own outlot, labeled Outlot H on the plans. Planned Unit Development Master Development Plan with Rezoning The subject property is currently zoned AG-Agriculture. The site itself was not included with the original Prestwick Place PUD that was approved in 2007, but the subdivision proposal is consistent with the standards for medium density development within the Prestwick Place PUD. Those standards allow a maximum of twelve units per building, a setback from public streets of 25 feet, a setback from property lines of 30 feet, minimum building separation of 20 feet, and a minimum parking setback of 20 feet. In addition to the standards specified in the PUD agreement, the Zoning Ordinance includes a section specific to single family attached housing. The proposed development plans meet or exceed these requirements as well as those for the City’s R3 zoning district. Phasing Development of the site will take place in two phases. The first phase of development will take place on the western portion of the site along the segment of Addison Avenue that has already been completed. The initial phase of development will contain 26 townhomes. The second phase will contain the remaining 24 units and it will be constructed after Addison Avenue is constructed to the eastern property line of the site. The necessary parking, both resident and guest, will be provided for each phase as it is developed. Street and Sidewalk System The site will be accessed via two private drives that allow a circular traffic movement through each development phase. A condition of approval is the construction of a sidewalk along the north and east Standard Prestwick Place PUD Requirement Proposed Prestwick 17th Max Units Per Building 6 12 8 Total Parking 2 driveway stalls per unit 2 garage stalls per unit .5 guest parking stalls 2 driveway stalls per unit 2 garage stalls per unit .5 guest parking stalls per unit 100 driveway stalls 100 garage stalls 27 guest stalls Street Setback 30 ft. 25 ft. 25 ft. (Addison Avenue) Property Line Setback 20 ft. 30 ft. 30 ft. Building Separation 20 ft. 20 ft. 22 ft. Setback to Private Dr. 20 ft. 20 ft. 20 ft. 5 side of Addison Avenue to connect with the sidewalk stub located at the northern property boundary along Addison Avenue. No sidewalks are proposed along the private streets within the site. Street 1 will be right-in/right-out only because it is located across from the start of the turn lane stripes along Addison Avenue. Street 2 is located across from the existing driveway to the Prestwick Place Townhomes site. The City Engineer’s memo includes a comment that the applicant adjusts the access point so Street 2 intersects Addison Avenue at a 90-degree angle and try to eliminate short street curves that may be awkward to navigate. An engineering memo dated February 26, 2019, is included as an attachment. Parks The proposed development was reviewed by the Parks and Recreation department. The City’s Parks Master Plan does not identify a new park in this area. Instead, the development will be served by Greystone Park, located 900 feet north of the site, and Ailesbury Park which is located roughly one quarter of a mile west of Akron Avenue along Connemara Trail. Staff recommends that cash be paid in lieu of land dedication for the 26 units in the final plat for Prestwick Place 17th Addition. The cash in lieu of land dedication for 26 units is $74,100 (26 units x $2,850 per unit). Stormwater Management Catch basins within Addison Avenue and the site’s private streets will collect stormwater and route it to the pond and infiltration basin located on Outlot H in the northeast corner of the site. The applicant will deed Outlot H to the city for ownership and maintenance of the storm water ponding and infiltration areas when the final plat is recorded. Landscaping The applicant has prepared a landscape plan that includes the installation of 100 trees and 330 foundation plantings. There are no existing trees on the site, so the applicant will not need to provide any replacement trees. In terms of the City’s landscaping requirements, the application meets or exceeds all City standards based on the zoning and number of dwelling units proposed. Landscaping Required Provided Trees 50 (1 tree per dwelling unit) 51 Deciduous 39 Evergreen 10 Ornamental Foundation Plantings 330 (1 shrub per 10 linear feet of building) 330 The landscape plan provides a good mix of deciduous and evergreen trees with enhanced planting along Addison Avenue. Foundation plantings are provided near the front walk and stoops of all units. Staff is recommending that one of the trees located atop a storm sewer be relocated to avoid root damage to the infrastructure below ground. This is noted in the engineer’s memorandum dated February 26, 2019, included in the attachments. Home Design The proposed townhome structures will be side-by-side, with structures varying in size from four to eight units. Each building will feature brick or stone elements as well as a combination of lap and shake siding. The front elevations feature gables to break up the roofline and add interest. The plans provided by the 6 applicant also show carriage-style garage doors on the units. The structures feature 360-degree architecture using two colors and decorative trim between the first and second floors. Look-out and walk- out buildings will have rear balconies while at grade units will have patios. Each unit will be approximately 1,700 square feet within two stories and feature three bedrooms and three bathrooms. Lighting Under the City’s zoning regulations, the townhouse project does not require a specific photometric lighting plan. Instead, the applicant has been advised that they will need to follow the City street lighting policy for Addison Street and the internal private road system. The City’s policy specifies the type and spacing of fixtures to be used. The final plan set does not include any information about street lights, and the final plans should be updated to include a specific lighting plan. CONCLUSION & RECOMMENDATION While this request was not part of the original Prestwick Place PUD, the site is guided for medium density residential development and was anticipated to be consistent with similar neighborhoods within the 2007 PUD. The applicant is requesting the PUD standards similar to those of the Prestwick Place PUD for medium density residential development, and the request meets all other standards of the R3-Medium Density residential zoning district. Staff is recommending approval of the Planned Unit Development Master Development Plan with Rezoning as well as approval of preliminary and final plats for Prestwick Place 17th Addition, subject to conditions. Dakota County, MN Property Information Februa ry 15, 2 019 0 875 1,750437.5 ft 0 270 540135 m 1:9,600 Disclaimer: Map and parcel data are believed to be accurate, but accuracy is not guaranteed. This is not a legal document and should not be substituted for a title search,appraisal, survey, or for zoning verification. Phone (952) 937-5150 12701 Whitewater Drive, Suite #300 Fax (952) 937-5822 Minnetonka, MN 55343 Toll Free (888) 937-5150 Phone (952) 937-5150 12701 Whitewater Drive, Suite #300 Fax (952) 937-5822 Minnetonka, MN 55343 Toll Free (888) 937-5150 Phone (952) 937-5150 12701 Whitewater Drive, Suite #300 Fax (952) 937-5822 Minnetonka, MN 55343 Toll Free (888) 937-5150 Phone (952) 937-5150 12701 Whitewater Drive, Suite #300 Fax (952) 937-5822 Minnetonka, MN 55343 Toll Free (888) 937-5150 x x x x x x x Phone (952) 937-5150 12701 Whitewater Drive, Suite #300 Fax (952) 937-5822 Minnetonka, MN 55343 Toll Free (888) 937-5150 Phone (952) 937-5150 12701 Whitewater Drive, Suite #300 Fax (952) 937-5822 Minnetonka, MN 55343 Toll Free (888) 937-5150 x x x x x LENNAR.COM LENNAR®Richmond 952-249-3000 16305 36th Ave. N. Suite 600, Plymouth, MN 55446 Elevations of a home may vary and we reserve the right to substitute and /or modify design and materials, in our sole opinion and without notice. Please see your New Home Consultant and home purchase agreement for actual features designated as an Everything’s Included feature, additional information, disclosures, and disclaimers relating to your home and its features. Plans are artist’s renderings and may contain options which are not standard on all models. Lennar reserves the right to make changes to plans and elevations without prior notice. Stated dimensions and square footage are approximate and should not be used as representation of the home’s precise or actual size. Any statement, verbal or written, regarding “under air” or “finished area” or any other description or modifier of the square footage size of any home is a shorthand description of the manner in which the square footage was estimated and should not be construed to indicate certainty. Garage sizes may vary from home to home and may not accommodate all vehicles. Visit Lennar. com or see a Lennar New Home Consultant for further details and important legal disclaimers. This is not an offer in states where prior registration is required. Void where prohibited by law. †Source - BATC, 2017 Top 25 Builders List. Copyright © 2018 Lennar Corporation. All rights reserved. Lennar, the Lennar logo, Everything’s Included and the Everything’s Included logo are U.S. registered service marks or service marks of Lennar Corporation and/or its subsidiaries. U.S. Home Corporation d/b/a Lennar – Lennar Sales Corp. – Broker License #40021205. MN Bldr. Lic # BC001413. CalAtlantic Group, Inc.; BC number is – BC736565. (25391) 04/30/18 MAIN LEVEL UPPER LEVEL 1,719 Sq. Ft. • 2 Stories • 3 Bedrooms • 3 Bathrooms • 2 Car Garage LENNAR.COM LENNAR®Richmond 952-249-3000 2 Stories | 3 Bedrooms | 3 Bathrooms | 2 Car Garage 1,719 Sq. Ft. LENNAR.COM LENNAR®St Croix 952-249-3000 16305 36th Ave. N. Suite 600, Plymouth, MN 55446 Elevations of a home may vary and we reserve the right to substitute and /or modify design and materials, in our sole opinion and without notice. Please see your New Home Consultant and home purchase agreement for actual features designated as an Everything’s Included feature, additional information, disclosures, and disclaimers relating to your home and its features. Plans are artist’s renderings and may contain options which are not standard on all models. Lennar reserves the right to make changes to plans and elevations without prior notice. Stated dimensions and square footage are approximate and should not be used as representation of the home’s precise or actual size. Any statement, verbal or written, regarding “under air” or “finished area” or any other description or modifier of the square footage size of any home is a shorthand description of the manner in which the square footage was estimated and should not be construed to indicate certainty. Garage sizes may vary from home to home and may not accommodate all vehicles. Visit Lennar. com or see a Lennar New Home Consultant for further details and important legal disclaimers. This is not an offer in states where prior registration is required. Void where prohibited by law. †Source - BATC, 2017 Top 25 Builders List. Copyright © 2018 Lennar Corporation. All rights reserved. Lennar, the Lennar logo, Everything’s Included and the Everything’s Included logo are U.S. registered service marks or service marks of Lennar Corporation and/or its subsidiaries. U.S. Home Corporation d/b/a Lennar – Lennar Sales Corp. – Broker License #40021205. MN Bldr. Lic # BC001413. CalAtlantic Group, Inc.; BC number is – BC736565. (25392) 04/30/18 MAIN LEVEL UPPER LEVEL 1,774 Sq. Ft. • 2 Stories • 3 Bedrooms • 3 Bathrooms • 2 Car Garage LENNAR.COM LENNAR®St Croix 952-249-3000 2 Stories | 3 Bedrooms | 3 Bathrooms | 2 Car Garage 1,774 Sq. Ft. Front Elevation Renderings Side & Rear Elevation Renderings Comparable Photos MEMORANDUM DATE: February 26, 2019 TO: Anthony Nemcek, Planner CC: Kim Lindquist, Community Development Director Brian Erickson, Director of Public Works/City Engineer Stacy Bodsberg, Planning & Personnel Secretary FROM: Stephanie Smith, Assistant City Engineer RE: Prestwick Place 17th Addition – Preliminary and Final Plat Review SUBMITTAL: The following review comments were generated from the following Prestwick Place 17th Addition documents prepared by Westwood Engineering: Preliminary Plat (dated 1/29/2019) Preliminary Plans (dated 1/29/2019) comprised of the following: ▫ Existing Conditions Survey ▫ Grading Plan ▫ Utility Plan and Profiles ▫ Street Plan and Profiles ▫ Landscaping Plan Preliminary Storm Water Report (dated 1/25/2019) Ghost Plat of Outlot I dated (1/29/2019) ASSESSMENTS AND FEES: 1. The development fees below are estimated based on the current Schedule of Rates and Fees. These fees are due with the final plat and subdivision agreement. Sanitary Sewer Trunk Charge: $1,075/acre Watermain Trunk Charge: $6,500/acre Storm Sewer Trunk Charge: $6,865/acre 2. Per the existing Joint Development and Cost Sharing Agreement, the developer is responsible for the costs of adjacent roadways attributed to “Tract 4B”. The fee will be due with the subdivision agreement and will be reconciled for the actual total cost of improvement once the streets have been constructed and accepted by Council. These costs are as follows: Prestwick Cost Share Spreadsheet: G:\ENGPROJ\431\Prestwick Place Cost Share Tabulation - 2019.xlsm The developer is responsible for costs associated with upgrading Akron Avenue. This cost is $248.67/acre. The developer is responsible for costs associated with the extension of Connemara Trail between Bloomfield and Akron Avenue. This cost is estimated at $2,269.41/acre. The developer is responsible for costs associated with the extension of Connemara Trail East approximately 0.25 miles. This cost is estimated at $6,926.04/acre. The developer is responsible for costs associated with the full construction of Addison Avenue. This cost is estimated at $35,148.80/acre. The applicant proposes to construct a segment of Addison Avenue with this project, so this cost may be reduced. 3. Plans must be signed by an engineer registered in the state of Minnesota. ROADWAYS: The applicant proposes the construction of Addison Avenue from the existing temporary cul-de-sac to the eastern property line. A temporary hammerhead-type end section would be constructed where future driveway approaches will be constructed. This is an acceptable end treatment as it will reduce the amount of pavement and curb and gutter reconstruction with future phases while still providing turnaround for emergency vehicles. 1. Callout the portion of the Addison Avenue profile that is based on plans by others. Include the note that wear course has not yet been installed. 2. The applicant shall install sidewalk on the northeastern side of Addison Avenue to connect to the existing sidewalk stub at the northern property line. 3. Revise intersection details to include the sidewalk. 4. “Future Thru Street” signage is required at the end of Addison Avenue. 5. A street lighting plan shall be submitted for review and must comply with City standards. Street light requirements are detailed below: at all public street intersections at the end of all cul-de-sacs at regularly spaced intervals (not to exceed 500’) on alternating sides of the street at all instances where the road configuration warrants extra illumination as determined by City Engineering Staff Two private streets, to be owned and maintained by a Homeowner’s Association, are proposed to provide access to the townhomes: Street 1 and Street 2. Street 1 will have a right-in/right-out access to Addison Avenue as the access is located across from the beginning of the turn lane stripes for Addison Avenue to 141st Street. 6. The applicant shall appropriately sign the intersection as “No Left Turn.” 7. The end of Street 1 shall be signed “No Parking” 8. The applicant’s engineer shall provide a turning movement inset to insure Lot 4, Block 3 has enough space to back out of the driveway. 9. Staff recommends high-back curb for the parking areas on Street 1. Street 2 accesses Addison Avenue across from the existing driveway to the Prestwick Place Townhomes site. 10. Street 2 alignment shall be adjusted to intersect Addison Avenue at a 90-degree angle and attempt to eliminate short tangents/curves that may be awkward to navigate. 11. All street names and intersections must be labeled in profile view of the construction plans. 12. The plans shall be revised to show locations and slopes of the driveways. RIGHT-OF WAY & EASEMENTS: The plat includes right-of-way dedication for Addison Avenue and drainage and utility easement to be dedicated as required. 13. Drainage and utility easements are required on Outlot A and will be required on Outlot D- FUT for the private streets. 14. Temporary roadway easements shall be dedicated for the construction of a temporary hammerhead at the end of Addison Avenue. 15. The width of drainage and utility easements over all public utilities shall be verified during final design and incorporated into the final plat. 16. The applicant shall deed Outlot H to the City for ownership and maintenance of the storm water ponding and infiltration areas concurrently with the final plat recording. 17. Signage for natural areas around the pond buffer shall be provided by the developer and a 3- year maintenance warranty shall be required to ensure establishment of the naturally vegetated areas. Costs associated with the establishment of the naturally vegetated pond buffer shall be a cost of the development. 18. The developer is required to coordinate with the gas pipeline owners to obtain all permits and agreements for grading and utility work within the pipeline easement areas. Copies of all agreements shall be submitted to the City prior to construction. 19. More information regarding the gas pipelines and easements are required on the plan. Contact information, pipeline sizes and material, and warnings should be shown. The developer is required to meet the plan requirements of the gas pipeline owners. Pothole elevations shall be provided during final design at each gas pipeline crossing location to verify the improvements can be constructed as proposed. 20. More information regarding transmission line “H” is required on the plan, whether this is for a future line or a line that has previously been abandoned. 21. Trees are not allowed to be planted within D&U easements, over the proposed storm sewer, or within a pond access location. WATER & SANITARY UTILITIES: The applicant proposes to connect to City water and sanitary sewer within Addison Avenue. The project also proposes to extend the Addison Avenue utilities to the eastern property line. Water and sanitary mainlines constructed in this project will be City-owned and maintained. 22. The applicant shall coordinate their schedule for utility connection with the City’s Addison Avenue project, CP 2018-06. 23. A hydrant is required for flushing the watermain stub at the end of Addison Avenue. 24. Two gate valves are required at three-legged intersections. 25. Staff recommends using a 0.50% slope for 8” sanitary sewer to insure that construction minimums are met. 26. Watermain and Sanitary Sewer will be revised during final design. Typical revisions will include number and placement of hydrants, gate valves and manholes. GRADING & DRAINAGE: The applicant’s plan proposes to collect stormwater from Streets 1-3 and Addison Avenue at on street catchbasins and direct the flow to a pond and infiltration basin on Outlot H. 27. Grading shall not direct stormwater runoff towards building pads. Revise contours or callout spot elevations to illustrate grading to prevent runoff to proposed structures. 28. Revise proposed contour 940 on Outlot E to tie-in to the existing contours. 29. Recommend shifting Blocks 5 and 6 to reduce the impervious surface from long driveways. 30. Show the location of the soil boring on the grading plan. Closest soil boring to infiltration basin is ST-14 with is approximately 500 feet away. Include boring ST-16 with Prestwick 17th Stormwater Management Report. 31. Include pond and infiltration basin cross section detail in grading plan. A 4:1 slope maximum is required above the normal water level. 32. Provide updated survey north of property boundary to reflect updated current grading from Greystone. Pond 1P HWL from Greystone III Hydrology Report should be included on the Prestwick 17th Grading plans: 100-yr HWL = 924.54’; 10-Day Snow Melt = 928.28’ 33. Annotate a maintenance access to all pond structures on the grading plan. The maintenance access shall be paved with an 8% maximum grade, 2% cross slope, minimum width of 10- feet, and a turnaround. 34. No permits were attached to the review. An NPDES Permit and SWPPP is required prior to the final plat. 35. Show location of topsoil stockpile in the erosion and grading plan. 36. Include the inlet protection symbol in the legend on the erosion control plan. 37. Add the following comment in the erosion control sequencing: Construct the NURP pond in the initial phase of grading to act as pretreatment of runoff during construction. Clean out any accumulated sediments after final restoration. STORMWATER MANAGEMENT: Stormwater runoff will be collected at catchbasins on Addison Avenue and Streets 1-3. Runoff collected in catchbasins will be routed to the pond and infiltration basin on Outlot H. 38. Revise the design of stormwater pipe from Street 1 to a more direct route to the ponding. 39. Review Prestwick Place Preliminary Grading Plan – East dated 06/20/07 for previously proposed offsite drainage routed to regional pond in Outlot H. Drainage area south of Addison Ave should be expanded to the high points shown on the previous grading plan and include storm sewer subs to meet spread requirements as required. 40. Separate Prestwick 17th parcel and offsite areas in report narrative annotating drainage area and impervious percentage for each. 41. Include offsite area to the east in drainage area maps and HydroCAD model to demonstrate existing runoff volume will not flow into proposed regional pond and to verify that all proposed low floor / low opening elevations meet the City’s freeboard requirements. 42. Ensure HWL in the plans to match the HWL in the HydroCAD model. City Engineering Guidelines do not allow for infiltration when calculating the pond’s HWL. 43. Show 100-year HWL, 100-year Volume and 10-day snow-melt HWL on grading plans as required by engineering guidelines. 44. Include an outlet control structure detail in the plan. Show the location of the outlet control structure on the grading plan in the NE corner of the site discharging on the Greystone 7th Outlot E. 45. Recommend the NURP pond be lined to allow the basin to hold the permeant pool of water. 46. Provide a detail of the pond EOF section in the plan. 47. Call out all EOFs from all low points. Indicate these locations on the grading plan with spot elevations and flow arrows. EOF from Addison Avenue, Sta. 6+00 missing. 48. Submit pipe sizing calculations for City review. Gutter flow must not exceed 300-feet and flow rates to each CB must not exceed 3.0 cfs. 49. All storm sewer pipe must be 15-inch RCP or larger. 50. Include intersection detail for Addison Ave Sta. 6+00 in construction plans. Ensure that low point is not in middle of intersection. 51. To comply with NPDES Construction Permit requirements any soils with an infiltration rate greater than 8.3 in/hr will need to be amended. Provide infiltration basin amendment plan for review. 52. Post-construction infiltration testing utilizing an ASTM approved method will be required to show compliance with section 16.11 of the NPDES Construction Stormwater Permit. 53. Table 3 should be updated with the following methodology - 1/12 ac-ft per ac per day calculation is used to calculate the required infiltration surface area in the infiltration basin. 54. Provide a minimum of 3.0-feet of freeboard from the basin HWL and the lowest adjacent building opening. Compliance will need to be confirmed after other comments are addressed. 55. Provide a minimum of 1.0-feet of freeboard from the basin HWL and the low floor elevation. The following buildings are not in compliance. Lots 5, 6, Block 1A; Lots 1-6, Block 2A; Lots 1-4, Block 3. 56. Clearly label low floor and low opening elevations on all building pads. Some text is difficult to read at scale drawn. 57. Provide 3’ sump structure on last manhole prior to discharge to pond: CBMH 104 and STMH 113. 58. Only use the VB-type grate at low point: CBMH 120 and 121. 59. Storm Sewer design information is required to confirm required easement widths. If the storm sewer is to be less than 10’ deep, the easement shall be a minimum of 20’ wide. If the storm sewer is 10’ deep or greater, then the easement shall be twice as wide as the depth. Should you have any questions or comments regarding the items listed above, please contact me at 651-322-2015. Attached: Memorandum RE: Prestwick 17th Plan Review by WSB Stormwater Report for Prestwick Place – 17th Addition, Outlot N – Rosemount, MN Prepared for: Lennar Corporation 16305 36th Avenue North, Suite 600 Plymouth, MN 55446 Prepared by: Robert Olson, PE Westwood Professional Services 12701 Whitewater Drive, Suite 300 Minnetonka, MN 55343 (952) 937-5150 Project Number: 0020660.01 Date: 01/25/2019 Prestwick Place 17th Addition - Outlot N January 25, 2019 ii CONTENTS List of Tables ............................................................................................................................ ii List of Exhibits ............................................................................................................................ ii INTRODUCTION ...................................................................................................................... 1 CITY REGULATIONS ............................................................................................................... 1 Rate Control ....................................................................................................................... 1 Volume Control .................................................................................................................. 1 Water Quality ..................................................................................................................... 1 EXISTING CONDITIONS ......................................................................................................... 1 PROPOSED CONDITIONS ....................................................................................................... 2 VOLUME CONTROL ................................................................................................................ 2 WATER QUALITY .................................................................................................................... 3 CONCLUSIONS......................................................................................................................... 3 TABLES Table 1: Existing Conditions Cover ................................................................................. 1 Table 2: Proposed Conditions Cover............................................................................... 2 Table 3: Volume Control Calculations ............................................................................. 2 Table 4: Pond Calculations ............................................................................................. 3 EXHIBITS Exhibit 1: Existing Conditions Map Exhibit 2: Grading and Drainage Plan Exhibit 3: HydroCAD Report for Proposed Conditions Exhibit 4: Geotechnical Data Exhibit 5: Atlas 14 Data Prestwick Place 17th Addition - Outlot N January 25, 2019 1 INTRODUCTION This stormwater report summarizes the analysis of the proposed Prestwick Place 17 th Addition which is Outlot N of the original Prestwick Place Plat near 141st Street East and the newly constructed Addison Avenue in Rosemount, MN. The 7.91 acre property is currently grass. The site is governed by the stormwater rules of the City of Rosemount. An existing conditions drainage map is Exhibit 1. The proposed drainage is shown in the Grading and Drainage Plan in Exhibit 2. The site was modeled in HydroCAD to analyze the proposed conditions (Exhibit 3). CITY REGULATIONS The project site is under the regulatory authority of the City of Rosemount (Stormwater Management Plan). The project site is in a Zone X, which means it is outside the FEMA floodplain. The site is considered a low vulnerability area within the City’s Drinking Water Supply Management Area (DWSMA). Rate Control The city requires the entire 100-year rain event be contained onsite, thus rate control is not modeled. Volume Control The city requires a development to provide 1/12 of an acre-foot/acre/day of infiltration for the entire site’s acreage. Water Quality The city requires treatment of storm water to NURP guidelines prior to discharge. EXISTING CONDITIONS In existing conditions the site is mostly grassed with a small parking lot that serves the business to the north. Site surface cover is listed in Table 1. Table 1: Existing Conditions Cover Cover Area [acres] Impervious 0.33 Pervious 9.22 Total 9.55 Prestwick Place 17th Addition - Outlot N January 25, 2019 2 Stormwater from the site drains overland and to the north/northeast offsite. Since the proposed site will contain the entire 100-year rain event, the existing conditions discharge from the site was not modeled. The rainfall distributions and depths that were used in the HydroCAD analysis are from Atlas 14 precipitation data. PROPOSED CONDITIONS The proposed site will consist of a 50 townhome units along with associated driveways and parking stalls. Proposed conditions cover is presented in Table 2. Table 2: Proposed Conditions Cover Cover Area [ac] Impervious 6.21 Pervious 3.34 Total 9.55 There are two major stormwater practices in the proposed design: a NURP pond and an infiltration basin. VOLUME CONTROL The infiltration basin is located along the south side of the proposed NURP pond. The City requires the infiltration basin drawdown the volume of the 1/12 acre-foot/acre/day within 24 hours. With a design infiltration rate of 3.0 inches/hour for “A” soils (SP), the practice can infiltrate 6 feet of water within 1 day. Further geotechnical information is being gathered to further confirm the infiltration rate of 3.0 inches/hour. Table 3: Volume Control Calculations Drainage Area [ac]9.55 1/12 acre-foot/acre/day (af)0.80 Volume Provided for 1/12 acre-foot (af)*0.98 100-year Runoff Volume (af)4.50 100-year Volume Provided @ HWL 928.90 (af)4.50 * 7,151 sf x 3”/hr /12 x 24 hr = 42,906 cf or 0.98 af The 100-year runoff volume is contained entirely within the pond and infiltration area of the site. Prestwick Place 17th Addition - Outlot N January 25, 2019 3 WATER QUALITY Water quality was based on the city requirement of dead storage volumes greater than the runoff from a 2.5-inch rainfall event over the contributing drainage area, see Table 5 below. The pond incorporates 3:1 maximum slopes to the outlet elevation, a 10:1 safety bench for a width of 10 feet below the NWL, and maximum 3:1 slopes below the bench. Table 4: Pond Calculations Required Dead Storage (af)0.94 Provided Dead Storage (af)1.67 CONCLUSIONS The proposed design meets City requirements for volume and water quality. Prestwick Place 17th Addition - Outlot N January 25, 2019 4 Exhibit 1 Existing Conditions Map Phone (952) 937-5150 12701 Whitewater Drive, Suite #300 Fax (952) 937-5822 Minnetonka, MN 55343 Toll Free (888) 937-5150 Prestwick Place 17th Addition - Outlot N January 25, 2019 5 Exhibit 2 Grading and Drainage Plan Phone (952) 937-5150 12701 Whitewater Drive, Suite #300 Fax (952) 937-5822 Minnetonka, MN 55343 Toll Free (888) 937-5150 Prestwick Place 17th Addition - Outlot N January 25, 2019 6 Exhibit 3 HydroCAD Report for Proposed Conditions 1S DA-P23 1P Pond P23 2P Inf P23 Routing Diagram for 2019Model Prepared by Westwood Professional Services, Inc., Printed 1/27/2019 HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr 240.00 hrs 10-day Snowmelt Rainfall=7.10", AMC=42019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 2HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: DA-P23 Runoff =10.80 cfs @ 119.28 hrs, Volume=5.460 af, Depth= 6.86" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 2.00-250.00 hrs, dt= 0.05 hrs Type II 24-hr 240.00 hrs 10-day Snowmelt Rainfall=7.10", AMC=4 Area (ac) CN Adj Description 9.550 85 1/8 acre lots, 65% imp, HSG B 9.550 85 98 Weighted Average, AMC Adjusted 3.342 35.00% Pervious Area 6.208 65.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 25.0 Direct Entry, Subcatchment 1S: DA-P23 Runoff Hydrograph Time (hours) 250240230220210200190180170160150140130120110100908070605040302010Flow(cfs)12 11 10 9 8 7 6 5 4 3 2 1 0 Type II 24-hr 240.00 hrs 10-day Snowmelt Rainfall=7.10" AMC=4 Runoff Area=9.550 ac Runoff Volume=5.460 af Runoff Depth=6.86" Tc=25.0 min AMC Adjusted CN=98 10.80 cfs Type II 24-hr 240.00 hrs 10-day Snowmelt Rainfall=7.10", AMC=42019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 3HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Summary for Pond 1P: Pond P23 Inflow Area =9.550 ac, 65.00% Impervious, Inflow Depth = 6.86" for 10-day Snowmelt event Inflow =10.80 cfs @ 119.28 hrs, Volume=5.460 af Outflow =3.30 cfs @ 119.50 hrs, Volume=5.429 af, Atten= 69%, Lag= 13.1 min Primary =3.30 cfs @ 119.50 hrs, Volume=5.429 af Routing by Dyn-Stor-Ind method, Time Span= 2.00-250.00 hrs, dt= 0.05 hrs Starting Elev= 924.00' Surf.Area= 15,953 sf Storage= 72,928 cf Peak Elev= 926.96' @ 123.86 hrs Surf.Area= 28,133 sf Storage= 140,076 cf (67,148 cf above start) Plug-Flow detention time= 2,792.0 min calculated for 3.755 af (69% of inflow) Center-of-Mass det. time= 713.5 min ( 8,066.6 - 7,353.1 ) Volume Invert Avail.Storage Storage Description #1 914.00'236,100 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 914.00 1,987 0 0 923.00 11,202 59,351 59,351 924.00 15,953 13,578 72,928 926.00 25,536 41,489 114,417 928.00 30,969 56,505 170,922 930.00 34,209 65,178 236,100 Device Routing Invert Outlet Devices #1 Primary 924.00'15.0" Round Culvert L= 25.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 924.00' / 923.90' S= 0.0040 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 1.23 sf Primary OutFlow Max=3.06 cfs @ 119.50 hrs HW=926.51' TW=926.24' (Dynamic Tailwater) 1=Culvert (Inlet Controls 3.06 cfs @ 2.49 fps) Type II 24-hr 240.00 hrs 10-day Snowmelt Rainfall=7.10", AMC=42019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 4HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Pond 1P: Pond P23 Inflow Primary Hydrograph Time (hours) 250240230220210200190180170160150140130120110100908070605040302010Flow(cfs)12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=9.550 ac Peak Elev=926.96' Storage=140,076 cf 15.0" Round Culvert n=0.013 L=25.0' S=0.0040 '/' 10.80 cfs 3.30 cfs Type II 24-hr 240.00 hrs 10-day Snowmelt Rainfall=7.10", AMC=42019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 5HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Summary for Pond 2P: Inf P23 Inflow Area =9.550 ac, 65.00% Impervious, Inflow Depth > 6.82" for 10-day Snowmelt event Inflow =3.30 cfs @ 119.50 hrs, Volume=5.429 af Outflow =0.83 cfs @ 123.96 hrs, Volume=5.429 af, Atten= 75%, Lag= 267.8 min Discarded =0.83 cfs @ 123.96 hrs, Volume=5.429 af Routing by Dyn-Stor-Ind method, Time Span= 2.00-250.00 hrs, dt= 0.05 hrs Peak Elev= 926.94' @ 123.96 hrs Surf.Area= 11,911 sf Storage= 27,504 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 253.5 min ( 8,320.1 - 8,066.6 ) Volume Invert Avail.Storage Storage Description #1 924.00'73,219 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 924.00 7,151 0 0 926.00 10,063 17,214 17,214 928.00 14,010 24,073 41,287 930.00 17,922 31,932 73,219 Device Routing Invert Outlet Devices #1 Discarded 924.00'3.000 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.83 cfs @ 123.96 hrs HW=926.94' (Free Discharge)1=Exfiltration (Exfiltration Controls 0.83 cfs) Type II 24-hr 240.00 hrs 10-day Snowmelt Rainfall=7.10", AMC=42019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 6HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Pond 2P: Inf P23 Inflow Discarded Hydrograph Time (hours) 250240230220210200190180170160150140130120110100908070605040302010Flow(cfs)3 2 1 0 Inflow Area=9.550 ac Peak Elev=926.94' Storage=27,504 cf 3.30 cfs 0.83 cfs MSE 24-hr 3 100-Year (Atlas 14) Rainfall=7.42"2019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 7HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: DA-P23 Runoff =52.23 cfs @ 12.35 hrs, Volume=4.500 af, Depth= 5.65" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 2.00-250.00 hrs, dt= 0.05 hrs MSE 24-hr 3 100-Year (Atlas 14) Rainfall=7.42" Area (ac) CN Description 9.550 85 1/8 acre lots, 65% imp, HSG B 3.342 35.00% Pervious Area 6.208 65.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 25.0 Direct Entry, Subcatchment 1S: DA-P23 Runoff Hydrograph Time (hours) 250240230220210200190180170160150140130120110100908070605040302010Flow(cfs)55 50 45 40 35 30 25 20 15 10 5 0 MSE 24-hr 3 100-Year (Atlas 14) Rainfall=7.42" Runoff Area=9.550 ac Runoff Volume=4.500 af Runoff Depth=5.65" Tc=25.0 min CN=85 52.23 cfs MSE 24-hr 3 100-Year (Atlas 14) Rainfall=7.42"2019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 8HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Summary for Pond 1P: Pond P23 Inflow Area =9.550 ac, 65.00% Impervious, Inflow Depth = 5.65" for 100-Year (Atlas 14) event Inflow =52.23 cfs @ 12.35 hrs, Volume=4.500 af Outflow =8.23 cfs @ 12.59 hrs, Volume=4.494 af, Atten= 84%, Lag= 14.5 min Primary =8.23 cfs @ 12.59 hrs, Volume=4.494 af Routing by Dyn-Stor-Ind method, Time Span= 2.00-250.00 hrs, dt= 0.05 hrs Starting Elev= 924.00' Surf.Area= 15,953 sf Storage= 72,928 cf Peak Elev= 928.42' @ 18.02 hrs Surf.Area= 31,650 sf Storage= 184,086 cf (111,158 cf above start) Plug-Flow detention time= 2,022.1 min calculated for 2.819 af (63% of inflow) Center-of-Mass det. time= 1,232.0 min ( 2,028.9 - 796.8 ) Volume Invert Avail.Storage Storage Description #1 914.00'236,100 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 914.00 1,987 0 0 923.00 11,202 59,351 59,351 924.00 15,953 13,578 72,928 926.00 25,536 41,489 114,417 928.00 30,969 56,505 170,922 930.00 34,209 65,178 236,100 Device Routing Invert Outlet Devices #1 Primary 924.00'15.0" Round Culvert L= 25.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 924.00' / 923.90' S= 0.0040 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 1.23 sf Primary OutFlow Max=7.93 cfs @ 12.59 hrs HW=927.70' TW=925.90' (Dynamic Tailwater) 1=Culvert (Inlet Controls 7.93 cfs @ 6.46 fps) MSE 24-hr 3 100-Year (Atlas 14) Rainfall=7.42"2019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 9HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Pond 1P: Pond P23 Inflow Primary Hydrograph Time (hours) 250240230220210200190180170160150140130120110100908070605040302010Flow(cfs)55 50 45 40 35 30 25 20 15 10 5 0 Inflow Area=9.550 ac Peak Elev=928.42' Storage=184,086 cf 15.0" Round Culvert n=0.013 L=25.0' S=0.0040 '/' 52.23 cfs 8.23 cfs MSE 24-hr 3 100-Year (Atlas 14) Rainfall=7.42"2019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 10HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Summary for Pond 2P: Inf P23 Inflow Area =9.550 ac, 65.00% Impervious, Inflow Depth = 5.65" for 100-Year (Atlas 14) event Inflow =8.23 cfs @ 12.59 hrs, Volume=4.494 af Outflow =1.03 cfs @ 18.21 hrs, Volume=4.495 af, Atten= 88%, Lag= 336.8 min Discarded =1.03 cfs @ 18.21 hrs, Volume=4.495 af Routing by Dyn-Stor-Ind method, Time Span= 2.00-250.00 hrs, dt= 0.05 hrs Peak Elev= 928.39' @ 18.21 hrs Surf.Area= 14,773 sf Storage= 46,901 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 496.8 min ( 2,525.7 - 2,028.9 ) Volume Invert Avail.Storage Storage Description #1 924.00'73,219 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 924.00 7,151 0 0 926.00 10,063 17,214 17,214 928.00 14,010 24,073 41,287 930.00 17,922 31,932 73,219 Device Routing Invert Outlet Devices #1 Discarded 924.00'3.000 in/hr Exfiltration over Surface area Discarded OutFlow Max=1.03 cfs @ 18.21 hrs HW=928.39' (Free Discharge)1=Exfiltration (Exfiltration Controls 1.03 cfs) MSE 24-hr 3 100-Year (Atlas 14) Rainfall=7.42"2019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 11HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Pond 2P: Inf P23 Inflow Discarded Hydrograph Time (hours) 250240230220210200190180170160150140130120110100908070605040302010Flow(cfs)9 8 7 6 5 4 3 2 1 0 Inflow Area=9.550 ac Peak Elev=928.39' Storage=46,901 cf 8.23 cfs 1.03 cfs MSE 24-hr 3 NURP Rainfall=2.50"2019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 12HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: DA-P23 Runoff =11.12 cfs @ 12.37 hrs, Volume=0.938 af, Depth= 1.18" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 2.00-250.00 hrs, dt= 0.05 hrs MSE 24-hr 3 NURP Rainfall=2.50" Area (ac) CN Description 9.550 85 1/8 acre lots, 65% imp, HSG B 3.342 35.00% Pervious Area 6.208 65.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 25.0 Direct Entry, Subcatchment 1S: DA-P23 Runoff Hydrograph Time (hours) 250240230220210200190180170160150140130120110100908070605040302010Flow(cfs)12 11 10 9 8 7 6 5 4 3 2 1 0 MSE 24-hr 3 NURP Rainfall=2.50" Runoff Area=9.550 ac Runoff Volume=0.938 af Runoff Depth=1.18" Tc=25.0 min CN=85 11.12 cfs MSE 24-hr 3 NURP Rainfall=2.50"2019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 13HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Summary for Pond 1P: Pond P23 Inflow Area =9.550 ac, 65.00% Impervious, Inflow Depth = 1.18" for NURP event Inflow =11.12 cfs @ 12.37 hrs, Volume=0.938 af Outflow =2.78 cfs @ 12.98 hrs, Volume=0.932 af, Atten= 75%, Lag= 36.6 min Primary =2.78 cfs @ 12.98 hrs, Volume=0.932 af Routing by Dyn-Stor-Ind method, Time Span= 2.00-250.00 hrs, dt= 0.05 hrs Starting Elev= 924.00' Surf.Area= 15,953 sf Storage= 72,928 cf Peak Elev= 925.05' @ 12.98 hrs Surf.Area= 20,972 sf Storage= 92,267 cf (19,339 cf above start) Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= 448.7 min ( 1,277.0 - 828.3 ) Volume Invert Avail.Storage Storage Description #1 914.00'236,100 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 914.00 1,987 0 0 923.00 11,202 59,351 59,351 924.00 15,953 13,578 72,928 926.00 25,536 41,489 114,417 928.00 30,969 56,505 170,922 930.00 34,209 65,178 236,100 Device Routing Invert Outlet Devices #1 Primary 924.00'15.0" Round Culvert L= 25.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 924.00' / 923.90' S= 0.0040 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 1.23 sf Primary OutFlow Max=2.78 cfs @ 12.98 hrs HW=925.05' TW=924.52' (Dynamic Tailwater) 1=Culvert (Barrel Controls 2.78 cfs @ 3.42 fps) MSE 24-hr 3 NURP Rainfall=2.50"2019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 14HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Pond 1P: Pond P23 Inflow Primary Hydrograph Time (hours) 250240230220210200190180170160150140130120110100908070605040302010Flow(cfs)12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=9.550 ac Peak Elev=925.05' Storage=92,267 cf 15.0" Round Culvert n=0.013 L=25.0' S=0.0040 '/' 11.12 cfs 2.78 cfs MSE 24-hr 3 NURP Rainfall=2.50"2019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 15HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Summary for Pond 2P: Inf P23 Inflow Area =9.550 ac, 65.00% Impervious, Inflow Depth = 1.17" for NURP event Inflow =2.78 cfs @ 12.98 hrs, Volume=0.932 af Outflow =0.60 cfs @ 15.20 hrs, Volume=0.933 af, Atten= 78%, Lag= 133.2 min Discarded =0.60 cfs @ 15.20 hrs, Volume=0.933 af Routing by Dyn-Stor-Ind method, Time Span= 2.00-250.00 hrs, dt= 0.05 hrs Peak Elev= 925.02' @ 15.20 hrs Surf.Area= 8,637 sf Storage= 8,057 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 136.2 min ( 1,413.2 - 1,277.0 ) Volume Invert Avail.Storage Storage Description #1 924.00'73,219 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 924.00 7,151 0 0 926.00 10,063 17,214 17,214 928.00 14,010 24,073 41,287 930.00 17,922 31,932 73,219 Device Routing Invert Outlet Devices #1 Discarded 924.00'3.000 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.60 cfs @ 15.20 hrs HW=925.02' (Free Discharge)1=Exfiltration (Exfiltration Controls 0.60 cfs) MSE 24-hr 3 NURP Rainfall=2.50"2019Model Printed 1/27/2019Prepared by Westwood Professional Services, Inc. Page 16HydroCAD® 10.00-19 s/n 02396 © 2016 HydroCAD Software Solutions LLC Pond 2P: Inf P23 Inflow Discarded Hydrograph Time (hours) 250240230220210200190180170160150140130120110100908070605040302010Flow(cfs)3 2 1 0 Inflow Area=9.550 ac Peak Elev=925.02' Storage=8,057 cf 2.78 cfs 0.60 cfs Prestwick Place 17th Addition - Outlot N January 25, 2019 7 Exhibit 4 Geotechnical Data Prestwick Place 17th Addition - Outlot N January 25, 2019 8 Exhibit 5 Atlas 14 Data NOAA Atlas 14, Volume 8, Version 2 Location name: Rosemount, Minnesota, USA* Latitude: 44.7458°, Longitude: -93.0819° Elevation: 934.1 ft** * source: ESRI Maps ** source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica, Deborah Martin, Sandra Pavlovic, Ishani Roy, Michael St. Laurent, Carl Trypaluk, DaleUnruh, Michael Yekta, Geoffery Bonnin NOAA, National Weather Service, Silver Spring, Maryland PF_tabular |PF_graphical |Maps_&_aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Duration Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 5-min 0.354 (0.273-0.458) 0.421 (0.325-0.546) 0.536 (0.412-0.698) 0.638 (0.488-0.834) 0.786 (0.586-1.07) 0.907 (0.660-1.26) 1.03 (0.727-1.47) 1.17 (0.790-1.71) 1.36 (0.883-2.04) 1.50 (0.953-2.29) 10-min 0.518 (0.400-0.671) 0.616 (0.475-0.799) 0.785 (0.604-1.02) 0.934 (0.714-1.22) 1.15 (0.858-1.57) 1.33 (0.966-1.84) 1.51 (1.07-2.15) 1.71 (1.16-2.50) 1.99 (1.29-2.99) 2.20 (1.40-3.36) 15-min 0.631 (0.488-0.819) 0.751 (0.580-0.975) 0.958 (0.736-1.25) 1.14 (0.871-1.49) 1.40 (1.05-1.92) 1.62 (1.18-2.24) 1.85 (1.30-2.62) 2.09 (1.41-3.05) 2.42 (1.58-3.65) 2.69 (1.70-4.10) 30-min 0.883 (0.682-1.15) 1.06 (0.814-1.37) 1.35 (1.04-1.76) 1.62 (1.24-2.11) 2.00 (1.49-2.74) 2.32 (1.69-3.21) 2.65 (1.87-3.77) 3.01 (2.03-4.40) 3.50 (2.28-5.28) 3.89 (2.47-5.94) 60-min 1.16 (0.892-1.50) 1.37 (1.06-1.78) 1.77 (1.36-2.30) 2.13 (1.63-2.79) 2.71 (2.03-3.75) 3.20 (2.34-4.47) 3.73 (2.64-5.35) 4.32 (2.93-6.36) 5.16 (3.37-7.82) 5.84 (3.70-8.91) 2-hr 1.43 (1.11-1.83) 1.68 (1.31-2.16) 2.18 (1.69-2.81) 2.66 (2.05-3.44) 3.41 (2.60-4.71) 4.08 (3.02-5.67) 4.81 (3.44-6.86) 5.63 (3.87-8.25) 6.81 (4.51-10.3) 7.80 (4.99-11.8) 3-hr 1.60 (1.25-2.04) 1.87 (1.47-2.39) 2.42 (1.89-3.10) 2.98 (2.31-3.83) 3.88 (2.98-5.35) 4.68 (3.49-6.51) 5.58 (4.02-7.96) 6.60 (4.57-9.66) 8.09 (5.39-12.2) 9.34 (6.02-14.1) 6-hr 1.88 (1.48-2.37) 2.19 (1.72-2.76) 2.82 (2.22-3.57) 3.47 (2.72-4.42) 4.55 (3.54-6.25) 5.52 (4.17-7.63) 6.62 (4.83-9.38) 7.87 (5.51-11.5) 9.72 (6.54-14.5) 11.3 (7.33-16.8) 12-hr 2.13 (1.70-2.66) 2.48 (1.97-3.10) 3.17 (2.51-3.97) 3.85 (3.04-4.85) 4.96 (3.88-6.70) 5.95 (4.51-8.10) 7.05 (5.18-9.85) 8.28 (5.85-11.9) 10.1 (6.86-14.9) 11.6 (7.63-17.2) 24-hr 2.46 (1.98-3.04) 2.79 (2.24-3.45) 3.46 (2.77-4.29) 4.14 (3.29-5.16) 5.26 (4.16-7.05) 6.28 (4.82-8.47) 7.42 (5.51-10.3) 8.71 (6.22-12.4) 10.6 (7.30-15.6) 12.2 (8.12-18.0) 2-day 2.85 (2.31-3.48) 3.16 (2.56-3.87) 3.81 (3.07-4.67) 4.48 (3.60-5.53) 5.60 (4.48-7.43) 6.63 (5.14-8.87) 7.79 (5.85-10.7) 9.12 (6.58-12.9) 11.1 (7.70-16.1) 12.7 (8.55-18.6) 3-day 3.13 (2.55-3.80) 3.43 (2.80-4.17) 4.08 (3.31-4.98) 4.76 (3.84-5.83) 5.89 (4.73-7.75) 6.93 (5.40-9.20) 8.10 (6.11-11.1) 9.44 (6.85-13.3) 11.4 (7.99-16.6) 13.1 (8.85-19.0) 4-day 3.35 (2.74-4.05) 3.67 (3.00-4.44) 4.34 (3.54-5.27) 5.03 (4.08-6.14) 6.17 (4.97-8.07) 7.21 (5.64-9.52) 8.39 (6.35-11.4) 9.72 (7.08-13.6) 11.7 (8.20-16.9) 13.3 (9.05-19.3) 7-day 3.88 (3.20-4.65) 4.29 (3.54-5.15) 5.08 (4.17-6.11) 5.83 (4.76-7.05) 7.01 (5.64-8.99) 8.05 (6.31-10.5) 9.19 (6.99-12.3) 10.5 (7.65-14.5) 12.3 (8.68-17.5) 13.8 (9.46-19.9) 10-day 4.38 (3.63-5.22) 4.87 (4.03-5.81) 5.76 (4.75-6.89) 6.57 (5.39-7.91) 7.80 (6.28-9.87) 8.84 (6.94-11.4) 9.95 (7.58-13.2) 11.2 (8.19-15.3) 12.9 (9.13-18.2) 14.3 (9.84-20.5) 20-day 5.94 (4.96-6.99) 6.62 (5.53-7.81) 7.77 (6.47-9.19) 8.74 (7.24-10.4) 10.1 (8.14-12.5) 11.2 (8.82-14.1) 12.3 (9.40-16.0) 13.4 (9.90-18.1) 14.9 (10.7-20.8) 16.1 (11.2-22.9) 30-day 7.32 (6.15-8.57) 8.16 (6.86-9.57) 9.53 (7.98-11.2) 10.6 (8.86-12.6) 12.1 (9.80-14.8) 13.3 (10.5-16.6) 14.4 (11.1-18.5) 15.5 (11.5-20.7) 16.9 (12.1-23.4) 18.0 (12.6-25.5) 45-day 9.14 (7.72-10.6) 10.2 (8.61-11.9) 11.8 (9.97-13.8) 13.1 (11.0-15.4) 14.8 (12.0-18.0) 16.1 (12.8-19.9) 17.2 (13.3-22.0) 18.3 (13.6-24.2) 19.7 (14.2-27.0) 20.6 (14.5-29.1) 60-day 10.7 (9.11-12.4) 12.0 (10.2-13.9) 13.9 (11.7-16.2) 15.4 (12.9-18.0) 17.2 (14.0-20.7) 18.6 (14.8-22.8) 19.8 (15.3-25.1) 20.9 (15.6-27.4) 22.2 (16.0-30.2) 23.0 (16.3-32.3) 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top Page 1 of 4Precipitation Frequency Data Server 1/13/2019https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=44.7458&lon=-93.0819&dat... PF graphical Back to Top Page 2 of 4Precipitation Frequency Data Server 1/13/2019https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=44.7458&lon=-93.0819&dat... Maps & aerials Small scale terrain Large scale terrain Large scale map + – 3km 2mi + – 100km 60mi + – 100km 60mi Page 3 of 4Precipitation Frequency Data Server 1/13/2019https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=44.7458&lon=-93.0819&dat... Large scale aerial Back to Top US Department of Commerce National Oceanic and Atmospheric Administration National Weather Service National Water Center 1325 East West Highway Silver Spring, MD 20910 Questions?:HDSC.Questions@noaa.gov Disclaimer + – 100km 60mi Page 4 of 4Precipitation Frequency Data Server 1/13/2019https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=44.7458&lon=-93.0819&dat... MEMORANDUM To: Kim Lindquist, Community Development Director Kyle Klatt, Senior Planner Anthony Nemcek, Planner Brian Erickson, City Engineer/Public Works Director Stephanie Smith, Assistant City Engineer From: Dan Schultz, Parks and Recreation Director Date: February 21, 2019 Subject: Prestwick Place – 17th Final Plat The Parks and Recreation Department recently reviewed the final plat for the Prestwick Place 17th Addition. After reviewing the plans, the Parks and Recreation Department staff has the following comments: PARKS DEDICATION The parks dedication requirement for the 26 units in the 17th addition is to be cash in lieu of land. The cash in lieu of land dedication for 26 units is $74,100 (26 units x $2,850 per unit). The cash dedication is to be paid prior to, or at the time of execution of the final plat. Please let me know if you have any questions about this memo.