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HomeMy WebLinkAbout15.D.2. Revised Design Criteria for Subdivisions-Res. No. 6053 CITY OF SHAKOPEE IS,O# ;L, Memorandum TO: Mayor & City Council Mark McNeill, City Administrator CONSENT FROM: Jeff Weyandt, Assistant City Engineer SUBJECT: Revised Design Criteria for Chapter 12 ofthe City Code Subdivision Regulations DATE: June 1,2004 INTRODUCTION: Attached is Resolution No. 6053, a resolution adopting the attached Revised Design Criteria for the Subdivision Ordinance. BACKGROUND: In the Subdivision Ordinance the section on Design Criteria was approved by resolution, instead of ordinance, in order to more readily change technical standards. The Design Criteria has not been revised since 1999. New text in the document has been underlined and text proposed to be deleted has a line through it so the revisions can be identified eaSIer. The Revised Design Criteria will clarify City requirements and help ensure current standards are being met. ALTERNATIVES: 1. Approve the proposed Design Criteria for the Chapter 12 Subdivision Ordinance as presented. 2. Approve the proposed Design Criteria for the Chapter 12 Subdivision Ordinance with reVISIons. 3. Do not approve the proposed Design Criteria. 4. Table for additional information. RECOMMENDATION: Approve the proposed Design Criteria for the Chapter 12 Subdivision Ordinance as presented. ACTION REQUESTED: Offer Resolution No. 6053, A Resolution Adopting Design Criteria for Chapter 12 of the City Code Subdivision Regulations and move its adoption. Jeff Weyandt Assistant City Engineer JW/pmp ENGRlEMPLOYEEFOLDERlPPENNINGTON/COUNCIlJMEM06053 RESOLUTION NO. 6053 A Resolution Adopting Design Criteria For Chapter 12 Of The City Code, Subdivision Regulations WHEREAS, the Shakopee City Council adopted Ordinance No. 557, an ordinance replacing Chapter 12, Subdivision Regulations on September 21, 1999; and WHEREAS, the Subdivision Regulations refer to adopted Design Criteria for the installation of public improvements; and WHEREAS, the City Council now desires to revise the City of Shakopee's Design Criteria to reflect current construction and new technologies. NOW, THEREFORE, BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF SHAKOPEE, MINNESOTA: that it hereby approves and adopts the Design Criteria, a copy of which is attached hereto for use with Chapter 12 of the City Code, Subdivision Regulations. BE IT FURTHER RESOLVED: that copies ofthe Design Criteria shall be kept in the office of the City Engineer and open for reference at all times. Adopted in session ofthe City Council of the City of Shakopee, Minnesota, held this day of ,2004. Mayor of the City of Shako pee ATTEST: City Clerk City of Shakopee Design Criteria Adopted: December 21, 1999 Revised: April, 2004 City of Shakopee Design Criteria Page 1 Table of Contents Design Criteria and General Plan ReQuirements - Grading, Street and Utility Improvements Sect. 1 General Sect. 2 Grading Sect. 3 Soil Erosion and Sedimentation Control Sect. 4 Storm Sewer Sect. 5 Sanitary Sewer Sect. 6 Utilities Sect. 7 Street Lights Sect. 8 Streets and Alleys Sect. 9 Sidewalks and Trails Sect. 10 Lots and Blocks Sect. 11 Plan Standards Sect. 1 - General I The requirements contained in this document are minimum general requirements for new construction. The City Engineer may require additional information and increase the minimum requirements on anyproiect. Sect. 2 - Grading 1. General. The grading and erosion control plans shall conform to the most recent editions of "Protectine Water Quality in Urban Areas"(Best Management Practices fOf Minnesota). "National Urban Runoff Prol!ram" (NURP). City of Shakopee "Comprehensive Stormwater Manaeement Plan" or as modified herein and the City's most recent Standard Detail Plates. 2. Gradine. Drainaee and Erosion Control. A. The minimum allowable grade in non paved areas is 2%. B. No final graded slopes shall be steeper than 3 feet horizontal to I foot vertical (3:1). C. Driveway grades shall be less than 10%, and greater than 1.0%. Driveway grades shall not be greater than 6% within 10' of the street edge the right- City of Shakopee Design Criteria Page 2 of-way. Commercial and Industrial Driveway grades shall not be greater than 6% for any part of the driveway. D. Lots shall be graded so as to provide drainage away from building locations.. 3. Topsoil - Sodding and Seeding. Topsoil moved during the course of construction shall be redistributed in turf establishment areas with a minimum of 4 Q inches of topsoil. Disturbed boulevard areas shall be seeded or sodded as required by the City Engineer. restored in accordance with the City of Shakopee General Specifications and Standard Detail Plates. 4. Drainage. During the grading of the site, the natural drainage system shall be utilized as much as feasible for the storage and flow of runoff. 5. As-built Grading Plan. Upon completion of the grading of subdivisions, an as-built survey ofthe grading shall be submitted to the City. This plan shall show the existing elevation of all lot corners, pads, top of curb, sidewalks, trails, storm sewer structures, emergency over flows and ponding areas. The plan shall certify that all ponding areas are within drainage and utility easements. Two benchmarks shall be shown on the as-built grading plan. No building permits shall be issued until this plan has been submitted and approved by the City Engineer. 6. Grading Permit. Grading Permits will be required, as described in Section 11.60, Subd. 6, ofthe City Code. 7. Tree Preservation Fence. Existing trees, which are to be saved, shall be protected with a tree preservation fence This fence shall be installed at the drip line to protect the trees 'lIhich are to be sa'/ed. installed at the drip line ofthe tree (s). No grading, construction materials, or equipment will be allowed beyond this fence. 8. Plan Requirements. The following are specific requirements related to the development of grading, drainage and erosion control plans for the proposed development and adjacent land within 200' unless noted otherwise: A. Show and label existing underground and overhead utilities. B. Show the location and indication of demolition or relocation of existing structures. C. Show lot corner elevations and benchmarks utilized. D. Existing contours shall be at I' or 2' intervals shown with dashed lines and screened. The contours shall extend beyond the proposed plat boundaries a minimum of 200' or as necessary to completely show the limits of a City of Shakopee Design Criteria Page 3 drainage basin not fully contained within the proposed plat. Ten-foot contour intervals shall be bold. E. Proposed contours shall be at I' or 2' intervals shown with solid lines. Ten-foot contour intervals shall be bold. F. Ponds, wetlands, lakes, streams or manholes shall be shown with the following: 1. Show the NWL and HWL for ponds and wetlands. 2. Show OHWL and DNR number if applicable. 3. Ponds shall include a lO-foot, 10:1 bench from the NWL to I-foot below the NWL. 4. Show the delineated wetland boundary. G. Show existing and proposed building footprints with proposed floor elevations. H. The lowest floor elevations of affected structuresadiacent to outletted ponds shall be in accordance with the City's Stormwater Management Plan. I. Show emergency overflow routes from all low points and show the high point elevation along emergency overflow routes. Show directional flow arrows. Emergency overflows shall be a minimum of I-foot below the lowest o-pening elevation of adiacent affected structures. J. Show limits of clearing and grubbing. K. For proposed retaining walls, identify top and bottom elevations of retaining wall. Retaining walls greater than 4- feet in height shall be designed and certified by a registered professional engineer. L. Show all lot numbers, block numbers, and drainage and utility easements. Sect. 3 - Soil Erosion and Sedimentation Control 1. Purpose The purpose of this Section is to promote the public health, safety, property and general welfare of the citizens of the City and to conserve the soil, water and related resources and to control erosion and sedimentation caused by land disturbing activities. 2. Administration The Building Official or the City Engineer (depending on the land disturbing activity) shall be designated as the Administrator ofthis Section. City of Shakopee Design Criteria Page 4 3. Activities Subiect to Erosion Control Measures A. Any land disturbing activity in residential, multi-family, commercial or industrial zones shall be subject to erosion control measures provided that: 1. An area of 10,000 square feet or greater will be disturbed by excavation, grading, filling or other earth moving activities resulting in the loss of protective vegetation; or, 2. Excavation or fill exceeding WQ 50 cubic yards; or, 3. The installation of underground utilities, either public or private, resulting in more than 300 linear feet of trenching or earth disturbance; or, B. Any subdivisions that require plat approval or a certified survey map. C. Agricultural lands used mainly for the production of food, general farming, livestock and poultry enterprises, nurseries, forestry, etc., are not subject to the provisions of this Section. D. Any other land disturbing activity for which the City Engineer determines to have the potential for substantial erosion. 4. Erosion Control Plans A. All land disturbing activities covered by this Section shall be required to have an approved erosion control plan on file with the City prior to any construction starting. B. The erosion control plan shall contain any such information necessary for the Building Official and the City Engineer to determine that adequate erosion control and sedimentation measures are proposed. As a minimum, a topographic map showing existing and proposed contours, location of any natural watercourses and drainage ways, the extent of the land disturbing activity and any erosion control measures shall be shown on the plans submitted and approved. C. In addition to the plans, a narrative report summarizing the proposed erosion control measures shall be submitted. This report shall include language discussing the timing of the installation, phasing, stabilization of all structures, maintenance and eventual removal of all structures. 5. Performance Standards City of Shakopee Design Criteria Page 5 A. General Standards. In general, this Section does not require the use of any particular type of structure to control erosion and sedimentation. The City Engineer or Building Official shall evaluate the proposed measures to determine if they follow current accepted design criteria and engineering standards. 1. The smallest practical area of land shall be exposed at any given time during development. 2. When soil is tmposed, the exposure shall be for the shortest period of time. Within 30 days of the rough grading, the site shall be seeded and mulched. Exposed soil shall be seeded and mulched. in accordance with NPDES Phase II reauirements. 3. All development shall conform to the natural limitations presented by the topography and soil as to create the best potential for preventing soil erosion. 4. Erosion control measures shall be coordinated with the different stages of development. Appropriate control measures shall be installed prior to development to control erosion. 5. The natural vegetation and plant covering shall be retained whenever possible. Temporary vegetation, mulching or other cover shall be used to protect critical areas and permanent vegetation shall be installed as soon as practical. B. Standards - Stormwater Runoff Erosion. 1. The natural drainage system shall be used as far as when and wherever is feasible for storage and flow of runoff Stormwater drainage shall be discharged to marsh lands, swamps, retention basins or other treatment facilities. Temporary storage area or retention ponds shall be considered to reduce peak flows, erosion damage and construction costs. If the drainage area is over five acres, a sediment basin shall be utilized. 2. Silt fence or hay bales shall be utilized to control erosion and prevent sedimentation from leaving the construction site. These structures shall be properly installed according to current standards the City of Shakopee Standard Specifications and Detail Plates. 3. If needed, sod shall be laid in strips at intervals necessary to prevent erosion and at right angles to the direction of drainage. City of Shakopee Design Criteria Page 6 4. At existing storm sewer inlets, temporary sedimentation traps may be necessary to prevent erosion from entering the storm sewer system, and downstream water bodies. 5. Adequate provision shall be made to prevent the tracking or dropping of dirt or other materials from the site onto any street by the use of; grayel pads at all rock construction entrances. C. Exposed Slopes. The following control measures shall be taken to control erosion during construction: 1. No exposed slope shall be steeper in grade than three (3) feet horizontal to one (1) foot vertical. 2. Exposed slopes steeper in grade than ten (10) feet horizontal to one (I) foot vertical shall be contour plowed to minimize direct runoff of water. 3. At the. foot of each exposed slope, a channel and berm shall be constructed to control runoff. The channeled water shall be diverted to a sedimentation basin (debris basin, silt basin or silt trap) before being allowed to enter the natural drainage system. 4. Along the top of each exposed slope, a berm shall be constructed to prevent runoff from flowing over the edge of the slope. Where runoff collecting behind said berm cannot be diverted elsewhere and must be directed down the slope, appropriate measures shall be taken to prevent erosion. Such measures shall consist of either an asphalt paved flow apron and drop chute laid down the slope or a flexible slope drain. At the base of the slope drain or flood apron, a gravel energy dissipater shall be installed to prevent erosion at the discharge end. 5. Exposed slopes shall be protected by whatever means will effectively prevent erosion considering the degree of slope, soils materials, and expected length of exposure. Slope protection shall consist of mulch, sheets of plastic, burlap or jut netting, sod blankets, fast growing grasses or temporary seeding of annual grasses. Mulch consists of hay, straw, wood chips, corn stalks, bark or other protective material. Mulch shall be anchored to slopes with liquid asphalt, stakes, and netting or shall be worked into the soil to provide additional slope stability. City of Shakopee Design Criteria Page 7 6. Control measures, other than those specifically stated above may be used in place of the above measures if it can be demonstrated that they will effectively protect exposed slopes. D. Dust Control Measures. 1. Temporary mulching or seeding shall be applied to open soil to minimize dust. 2. Barriers such as snow fences, commercial wind fences and similar materials shall be used to control air currents and blowing soil if the City Engineer determines it is necessary. 3. The exposed soil shall be watered to control dust, with frequency of watering repeated as necessary. 4. Permanent vegetation shall be established as quickly as possible. 'Nithin 30 days after the rough grading has been completed the entire area shall be seeded and mulched in accordance with NPDES Phase IT requirements. 6. Maintenance of Erosion Control Measures A. The owner or developer shall be responsible for maintaining all erosion control structures in a condition that will ensure continuous functioning of those devices. If, after the installation of the erosion control structure, the City Engineer determines that additional measures are needed, they shall be installed at the expense of the owner. B. Any erosion or sediment that runs off or blows off the site onto adjoining properties, City streets, storm sewers, etc., shall be the responsibility of the owner or developer for clean up and restoration. If the owner fails to properly clean up or restore all areas affected by erosion the City will hire a contractor to complete the work and bill the owner for the expenses associated with the clean-up. 7. Technical Reference The City officially designates the "Protecting Water Quality in Urban Areas" prepared by the Minnesota Pollution Control Agency as the technical reference for this Section. This reference will be used to ensure the proper placement and installation of any proposed erosion control structures. 8. Performance Bond The owner or developer shall submit to the City either a cash bond, an irrevocable letter of credit or other financial security to guarantee the faithful execution of the erosion control plan. This security shall be in the amount of 125% of the costs for construction of all erosion control devices and site restoration, including the costs of City City of Shakopee Design Criteria Page 8 inspection and administration (as approved by the City Engineer). The City is authorized to draw against this security in the event the erosion control plan is not followed. 9. Unlawful Acts It is unlawful for any person, either by the owner or the occupant of premises, to violate, neglect or refuse to comply with the requirements of this Section. ill addition, if the Building Official or the City Engineer determines that adequate erosion control measures are not being followed and there is little cooperation on the part of the owner to do so, a "stop work" order may be issued to the land disturbing acti'lity all work on the site until such times as adequate measures are implemented. In all cases, the ov;ner may appeal the "stop work" decision to the Council for re'/iew. Sect. 4 - Storm Sewer 1. Desi2:n Criteria. A. The design criteria, policies, and objectives shall be those described in the City's "Comprehensive Stormwater Management Plan". No existing ditch, stream, wetland, pond, drain or drainage canal shall be deepened, widened, filled, re-routed or filled without approval from the City Council. B. Storm sewer shall be designed to have a minimum full flow velocity of 3 ft/s. C. Storm sewer structures exceeding 4 feet in depth shall have a minimum diameter of 48 inches. 2. Pond Slopes. Pond slopes below the HWL shall not be steeper than 4 feet horizontal to 1 foot vertical. All ponds shall have a "bench" at the normal water level. This bench shall be a minimum of 10 feet wide and the slope of this bench shall not be steeper than 10 feet horizontal to 1 foot vertical. 3. Plan Requirements. A Stormwater Management Plan, along with supporting documentation, must be prepared and submitted that meets City drainage standards. Outlined below, please find a listing of information to be submitted: A. Drainage reports and studies shall include an overall drainage plan. The information listed below, ifnot shown on the drawings, shall be included in the report. The use of appropriate forms and design aids is recommended. 1. Runoff rate and ponding calculations for the site for the 2-year, 10- year and 100- year rainfall events and the 100- year, 10-day snow melt event. These computations should be provided for both the existing and future conditions, or as necessary to demonstrate City of Shakopee Design Criteria Page 9 compliance with the City's Stormwater Management Plan. Computations shall identify the critical duration of the rainfall events. 2. Open channel flow calculations/computations. 3. Storm sewer and storm inlet flow calculations for the 10-year rainfall event. 4. Culvert design flow calculations for the 10-year and 100-year rainfall events. 5. Summation of all design variables used and design assumptions made. 6. Soil classification reports and depth of underground water table throughout the study area when detention or retention ponds are used. 7. The boundary and designation of all tributary drainage areas and the area of each in acres. 8. The designation and location of each design point referred to in the calculations. 9. The reference source and a coPY of all other monographs or design aids used in the calculations. B. The preliminary drainage report shall be approved by the City Engineer prior to Engineering approval of any Preliminary Plat or Preliminary P.D.D. The study will consist of calculations, comments and descriptions on 8-1/2" x 11" paper and an area map on one 22" x 34" drawing. Calculations shall include the 2-year, 10-year, and 100-year rainfall events and the 100- year, 10-day snow melt event calculations of all tributary areas to the development, all collection points within the development and all points discharging from the development. The 22" x 34"map shall be a topographic map of both the development and all areas tributary to the development. The map shall show the total acreage and anticipated runoff rates at all points noted in the calculations. In addition, the map shall show the proposed location of all drainage facilities to be located within the development and their relationship to existing facilities in adiacent developments. Any scale from III = 50' to 1" = 400' may be used to limit the drawing to one sheet. C. A. final drainage report shall be submitted and approved in coniunction . ,. -. City of Shakopee Design Criteria Page 10 with construction drawings. The studv shall include calculations on 8-112" x II" paper and a drainage map ofthe development of 22" x 34" drawing, Calculations shall address all aspects of runoff, retention, detention, channel flow. or other appropriate information that is necessary for the design of the drainage system. The drainage map shall be prepared on the overall grading plan for the development. It shall illustrate the drainage patterns in the development as well as the location of all drainage facilities within the development. The map shall also show the runoff rates and acreage tributary to all collection points within the development. When intersections serve as collector points, the flow in each curb line must be noted. This drawing may use scales from 1" = 50' to l' = 200', in order to limit the drawing to one sheet. When more than one sheet is used a scale of 1 " = 200' shall be utilized. D. An overall drainage plan of the study area. including all areas outside of the study area, which contribute runoffto the study area and all downstream areas, which will be effected. by runoff from the study area, must be submitted. Drainage area plans shall be submitted showing the effects of the 2-year, 10-year and 100-year rainfall events and the 100- year, 10-day snow melt event. E. The following methods shall be used to verify the adequacy of designs submitted for approval: The method used shall be approved by the City Engineer. 1. Rational method for storm sewer design computations and peak discharge rates from a single isolated watershed. 2. Urban Hydrology for Small Wetlands Technical Release No. 55 and Technical Release No. 20 published by Soil Conservation Service. U.S. Department of Agriculture. 3. HEC-1, HEC-2, orHEC-RAS. 4. Minnesota Hydrology Guide published by Soil Conservation Service, U.S. Department of Agriculture. 5. Stormwater treatment ponds designed to NURP standards. F. The following criteria shall be utilized in the analysis of the drainage system. 1. Runoff analysis shall be based upon proposed land use, and shall take into consideration all contributing runoff from areas outside of the study area. City of Shakopee Design Criteria Page 11 2. The analysis of storm runoff from existing developed areas lying outside of the study area shall be based upon present land use and topographic features. 3. All undeveloped land lying outside of the study area shall be considered as fully developed based upon the most probable anticipated future land use. Provided, however, that whenever the future land use of a specific undeveloped area cannot be accurately predicted, the average runoff coefficient to be used in said area shall not be less than 0.60 for the Rational Method runoff coefficient or an approved equivalent value for any other method. 4. The probable future flow pattern in undeveloped areas shall be based on existing natural topographic features (existing slopes, drainage ways, etc.) and shall conform to the Comprehensive Storm Water Management Plan. 5. Average land slopes in both developed and undeveloped area may be used in computing runoff. However, for areas in which drainage patterns and slopes are established, these shall be utilized. 6. Flows and velocities which may occur at a design point when the upstream area is fully developed shall be considered. Drainage facilities shall be so designed such that increased flows and velocities will not cause erosion damage. 7. The use of on-site detention and natural drainage ways is recommended and encouraged whenever possible. The changing of natural drainage way locations will not be approved unless such change is shown to be without unreasonable hazard and liability, substantiated by thorough analysis and investigation. 8. The planning and design of drainage systems shall be such that problems are not transferred from one location to another. Outfall points shall be designed in such a manner that will not create flooding hazards downstream. G. The rainfall intensities to be used in the computation of runoff shall be obtained from the Intensity - Duration - Frequency Curves for the Monticello area as contained in the MnJDOT Drainage Manual and shall be based upon a 2 year, 10 year and 100 year return frequency. - City of Shakopee Design Criteria Page 12 H. All lateral storm sewer facilities shall be designed to accommodate a 1 Q-year rainfall event. The initial 1 O-year storm shall be conveyed without surcharging the system. Low points on streets shall be designed with an acceptable emergency overflow route. I. Storm sewer pipe for all public systems and connection to public systems shall be RCP. J. Connections to existing manholes or catch basins shall be core drilled. K. Driveway culverts in rural areas shall be at least 18 inches in diameter. Sect. 5 - Sanitary Sewer 1. General. The minimum diameter for public sanitary sewer mains shall be 8" diameter. Sanitary sewer design must account for the study area and all areas outside the study area which would naturally drain through the study area. Natural drainage areas will be established by using the Comprehensive Sewer Plan and Comprehensive Stormwater Management Plan adopted by the City. fu no case shall the design velocity be less than 2.2 feet per second nor more than 10.0 feet per second as computed by Mannings formula for flow in open channels (Mannings shall be 0.013 for purposes of design). 2. Desien Criteria. Sanitary sewers shall be designed and constructed in accordance with the most current edition of Recommended Standards for Sewage Works; a report of Committee of. the Great Lakes - Upper Mississippi River Board. of State Sanitary Engineers. 3. Plan Requirements and Desien Guidelines. The following are specific requirements related to the design of sanitary sewer and sanitarv sewer services: A. The sanitary sewer alignment shall follow the centerline of the street where practical. B. The maximum spacing between manholes is 400' unless approved otherwise. C. All manholes at intersections shall be located at centerline/centerline. D. Manholes are required on the terminus end of all stubs if the line will be active. E. Connections to existing sanitary sewer manholes shall be core-drilled and City of Shakopee Design Criteria Page 13 fitted with a watertight boot. F. Inside drop manholes are not allowed. G. Changing of pipe material between manholes is not permitted except at outside drops. H. Sanitary sewer services shall be a minimum 4" diameter PVC (SDR 26). I. Sanitary sewer services shall not be connected to a manhole unless otherwise approved. J. The minimum depth ofthe sanitary sewer service at the easement line shall be 9' unless otherwise approved. K. Sanitary sewer pipe shall be PVC SDR 35 (0 - 18' deep) and PVC SDR 26 (18' - 26') deep. Alternate pipe materials for sanitary sewer deeper than 26 feet will be required as determined by the City Engineer. L. Rerounding of pipe is not allowed unless previously approved by the City Engineer. Sect. 6 - Utilities 1. Public Water. Where a connection to the City water system is presently available at or reasonably near the boundary of the subdivision, water distribution facilities, including fire hydrants, shall be installed to serve all properties within the subdivision and shall be in accordance with policies of the Shakopee Public Utilities Commission. Public Water systems shall be designed and constructed in accordance with the standards and policies ofthe Shakopee Public Utility Commission. 2. Other Utilities. Electric service, phone service, and cable television. installations to residential structures shall be underground from the main line to the residential structure except where extreme conditions prohibit and a variance from this requirement is authorized by the Planning Commission upon advice of the Utilities Commission. Provisions shall also be made for underground connections of street lights as required from main lines to the street line installation. Where telephone, electric and/or gas service lines are to be placed underground, conduits or cables shall be placed within easements or dedicated public ways, in such a manner so as not to conflict with other underground services, and in locations as approved by the City Engineer. All drainage and other underground utility installations that traverse privately owned property shall be protected by easements. City of Shakopee Design Criteria Page 14 Sect. 7 - Street Lights Desi2n Criteria. The subdivider shall provide for installation of street lighting and operation for a period of three (3) years as prescribed by the Utilities Manager. Street lighting shall be designed and constructed in accordance with the standards and policies of the Shakopee Public Utility Commission and the City of Shako pee. Sect. 8 - Streets and Alleys 1. General. A. The arrangement of thoroughfares and collector streets shall confonn as nearly as possible to the Comprehensive Plan. Except for cul-de-sacs, streets nonnally shall connect with streets already dedicated in adjoining or adjacent subdivisions, or provide for future connections to adjoining unsubdivided tracts, or shall be a reasonable projection of streets in the nearest subdivided tracts. The arrangement of thoroughfares and collector streets shall be considered in their relation to the reasonable circulation of traffic, to topographic conditions, to runoff of stonnwater, to public convenience and safety, and in their appropriate relation to the proposed uses ofthe area to be served. B. Where the plat to be submitted includes only part of the tract owned or intended for development by the subdivider, a tentative plan of a proposed future street system for the unsubdivided portion shall be prepared and submitted by the subdivider at the same scale as set forth herein. C. When a tract is subdivided into larger than nonnal building lots or parcels, such lots or parcels shall be so arranged so as to permit the logical location and openings of future streets and appropriate resubdivision, with provision for adequate utility connections for such resubdivision. 2. Street Width and Ri2ht-of-Wav Width. A. Two-way right-of-way widths and pavement widths (face to face back to back of curb) shall confonn to the City's adopted Transportation Plan, with the exception of the local roads. The local road width shall be as follows: Classification Right-of-Way Roadway Local (anticipated traffic of200, or less, cars per day, as detennined City of Shakopee Design Criteria Page 15 by the City Engineer) 60 Feet ~ 33 Feet Local (more than 200 cars per day) 60 Feet *-37 Feet B. All one-way right-of-way widths and pavement widths (face to face back to back of curb) shall conform to the following minimum dimensions: Classification Right-of- W ay Roadway Local 45 Feet ~ 25 Feet Collector Streets 60 Feet 28 30 Feet Arterial Streets 60 Feet 28 30 Feet ~ Industrial or Commercial 20 Feet 16 Feet Residential (where permitted) 16 Feet 12 Feet (payement Width) 3. Streets. A. Public Streets and alleys shall be designed and constructed in accordance with the Construction Standard Specifications for Public Works. All street and alley construction shall be inspected by the City Engineering Department. B. The full width of the right-of-way of each street and alley dedicated in the plat shall be graded. The width shall comply with the surface provisions of this Chapter and Class V MNIDOT aggregate or other suitable base shall be required as prescribed by the Engineering Department. c. All streets shall be surfaced with a bituminous surface or portland cement concrete. D. Except where justified by special conditions, such as the continuation of an existing alley in the same block, alleys will not be approved in residential districts. Dead end alleys shall be avoided, whenever possible, but if unavoidable, such dead end alleys must provide adequate turnaround facilities at the closed end. E. Concrete curb and gutter may be required as a part of the required street surface improvement and shall. thus be designed for installation along both City of Shakopee Design Criteria Page 16 sides of all roadways in accordance with the standards of the City. The City shall inspect aU construction. F. Rural roadway sections, that do not include concrete curb and gutter, shall consist of roadside ditches and 5 foot gravel shoulders. 4. Grades. All center line gradients shall be at least 0.5 percent and shall not exceed the following: Classifications Gradient Percent Arterial Streets 5 Collector Streets 6 Local Streets 7 Marginal Access Streets 7 Alleys 8 The grades at intersecting state-aid streets shall notbe greater than 0.5% for 50' on either side of the state-aid street, and not greater than 2.0% for an additional 50'. The grades at intersecting arterial streets shall not be greater than 2.0% for 200' on either side of the intersection. On local streets, the grade shall not be greater than 3.0% for 100' on either side of the intersection. The more important street at an intersection, as determined by the City Engineer, shall govern the through grade. 5. Street JOf!.s. Street jogs (intersections less than 330 feet apart) must be approved by the City Engineer. 6. Local Streets. Local streets shall be so aligned that their use by through traffic will be discouraged. Dead end streets are prohibited, but cul-de-sacs will be permitted where topography or other conditions justify their use. 7. Cul-de-sacs. A. Maximum length of cul-de-sac streets shall be 1,000 feet for rural service areas and 750 feet for urban service areas measured along the center line from the intersection of origin to end of right-of-way. Cul-de-sacs shall have a dedicated right-of-way with a minimum radius of 60 feet, and shall be paved with a minimum radius of # 46 feet (to faee-back of curb). Lot lines abutting cul-de- sacs shall be radial except in extreme cases where special permission may be granted otherwise. 8. Temporary Cul-de-sacs. In new subdivisions where a future public street will connect to a temporary street stub, a temporary cul-de-sac will be required. The maximum length of City of Shakopee Design Criteria Page 17 temporary cul-de-sac streets shall be 750 feet for both rural service and urban service areas, measured along the center line from the intersection of origin to end of pavement. The minimum paved surface diameter shall be W-- 72 feet, without curb and gutter. A temporary cul-de-sac will not be required for street stubs that serve less than 3 lots. 9. Service Roads. Where a subdivision. abuts or contains an existing or planned service road or a railroad right-of-way, the Council may require a street approximately parallel to and on each side of such right-of-way for adequate protection of residential properties and to afford separation of through and local traffic. Such marginal. access streets shall be located at a distance from the major thoroughfares of railroad right-of-way suitable for the appropriate use of the intervening land, as for park purposes in residential districts, or for commercial or industrial purposes in appropriate. districts. Such distances shall also be determined with due regard for the requirements of approach grades and future grade separations. c 10. Half Streets. Half streets shall be prohibited, except where essential. to the reasonable development of the subdivision in conformity with the other requirements of these regulations; and except where the Council finds it will be practicable to require the dedication of the other half when the adjoining property is .subdivided. Wherever there is a half street adjacent to a tract to be subdivided, the other half of the street shall be platted within such tract. 11. Surface. All street surfaces shall be designed and constructed in accordance with the standard specifications and shall have a one year warranty period after being completed and accepted by the City Engineer, provide a warranty bond before being accepted by the City for maintenance. Curb and gutter or shoulder and bituminous surfacing shall be constructed at the same time. 12. Reserve Strips. Reserve strips controlling access to streets shall be prohibited. 13. Hardship to Owners of Adioinin2 Property Avoided. The street arrangement shall not be such as to cause hardship to owners of adjoining property in platting their own land and providing convenient access to it. 14. Access to Arterial and Collector Roadwavs. In the case where a proposed plat is adjacent to an arterial or collector road, the applicant shall not direct vehicle or pedestrian access from individual lots to such roadways. The subdivider will be required to provide access to all lots via public streets. Spacing of these public streets shall meet the requirements of the City's adopted Transportation Plan. 15. Plattin2 of Small Tracts. In the platting of small tracts of land fronting arterial roadways where there is no convenient access to existing entrances and where access from such plat would be closer than 1/4 mile from an existing access point, a service road 40 feet wide shall be dedicated across the tract. As the neighboring land is platted and developed, City of Shakopee Design Criteria Page 18 and access becomes possible to the service road, direct access to the thoroughfares shall be prohibited. 16. Deflections/Horizontal Curves. When connecting street lines deflect from each other at anyone point by more than 10 degrees, they shall be connected by a curve with a radius of not less than 120 2()Q-feet. Depending on grades and proiected traffic volumes the City Engineer may require a larger radius. This minimum curve radius does not apply to intersecting street lines (full street intersections) or to street lines connected at "T" intersections. Collector street horizontal centerline curves shall meet State Aid Standards not OO'/e a radius of less than 155 feet. 17. Street Vertical Curves The follo'Ning desired design speeds and minimum vertical curve le-ngths shall be used for street profiles: Vertical curves on local roads shall be designed to meet a design speed of 30 mph. The City Engineer will determine the design speed for arterial and collector roads. The minimum allowable curve length is 50 feet unless Design l\linimum Speeds Vertieal Curve Length .L\rterial Street 50 mph 150 feet Collector Street 15 mph 13 0 feet Local Street 35 mph 100 feet the algebraic difference between grades within a vertical curve is less than 1.2 percent, then the allowable minimum vertical curve length is ~ 20 feet. 18. An21e of Intersections. The angle formed by the intersection of streets shall be 90 degrees. Any variance will require approval by the City Engineer. 19. Size of Intersection. Intersections of more than four comers shall be prohibited. 20. Curb Return Radius. Minimum curb return radius at intersections shall conform to the following table: Curb Return Radius (feet) at Intersections Local~ Local ~) Collector Arterial QD (37') Local (~' 33' wide) 20 Local (W 37'wide) 20 l$-20 Collector 25 ~ 25 ;w... 25 Arterial 30 25 25 25 Industrial 30 25 25 25 City of Shakopee Design Criteria Page 19 The City Engineer may require larger radii. 21. Crosspans. Double crosspans may be used at the intersection of residential streets only when necessary to prevent flooding of one side of the street. Crosspans are not allowed across. collector or arterial streets. Crosspans are not allowed on streets with storm sewer systems or on other streets designated by the City Engineer. 22. Street Section Design The street section shall be designed as set forth in the "Road Design Manual" 5-291.523 and 5.291.524, as prepared by the Minnesota Department of Transportation. It shall be accompanied by a complete soils report certified by a Registered Professional Engineer. The following minimum pavement thickness and aggregate thickness shall apply to all streets: Minimum Minimum Bituminous Pavement Aggregate Base Arterial Street ~ 5" ~ 10" Collector Street (Residential)~ 4" ~ 8" Collector Street (Commercial) ~ 5" ~ 10" Collector Street (Industrial) ~ 5" ~ 10" Local Street 3 1/2" 4" ~ 8" The pavement section may be increased by the City Engineer based on the soils report. Sect. 8 - Sidewalks and Trails 1. Sidewalks A. The sidewalks shall not be located less than one foot from the property line, nor be adjacent to the curb except as determined in commercial areas. Sidewalks in industrial areas shall be located to conform to the anticipated pedestrian flow of the development. B. Sidewalks shall slope 1/4 inch per foot away from the property line and the profile grades shall conform to street grades. C. Planned unit development shall be subject to the location, widths, and grades set forth herein. D. The subdivider shall install sidewalks on both sides of an officially designated arterial street and on one side of collector streets, and walkways to schools; such collector streets and walkways to be determined by the City of Shakopee Design Criteria Page 20 Planning Commission and approved by the Council. If the street is along a designated trail route, a bituminous trail may be required in place of the sidewalk, as determined by the Planning Commission and approved by the Council. E. In blocks over 900 feet long, pedestrian crosswalks through the blocks, and at least 10 feet wide, may be required by the Council in locations deemed necessary to public health, convenience and necessity. F. Curb returns and intersections where sidewalk is required shall have handicap ramps. G. All sidewalks widths shall be 5 feet, except in commercial areas where the width may be wider, as determined by the City Council. Sect. 10 - Lots and Blocks 1. Easements A. Easements across lots or centered on rear or side lot lines shall be provided for utilities and drainage where necessary and shall be at least 10 feet wide for telephone or power line easements and 20 feet wide for drainage, sewer or water easements. Underground utility installation shall be required. B. Where a subdivision is traversed by a water course, drainageway, channel or stream, there shall be provided a stormwater easement or drainage right-of- way conforming substantially with lines of such watercourse, and such further width or construction, or both, as will be adequate for the purpose. Parallel streets or parkways may be required in connection therewith. C. Drainage and utility easements shall be shown on the final plat, out to the 100- year high water level contour. D. Access easements, for future maintenance, shall be provided for ponding areas within subdivisions. 2. Blocks A. Block length and width or acreage within bounding streets shall be such as to accommodate the size of residential lot required in the area by the Zoning Chapter and to provide for convenient access, circulation control and safety of street traffic. City of Shakopee Design Criteria Page 21 B. Residential block lengths shall not exceed 1,300 feet. Blocks intended for commercial and industrial use must be designed as such, and the block must be of sufficient size to provide for adequate off-street parking, loading and such other facilities as are required to satisfy the requirements of the Zoning Chapter of the City Code. C. A block shall be so designed as to provide two tiers of lots, unless it adjoins a railroad or major thoroughfare where it may have a single tier oflots. 3. Lot Standards A. The lot dimensions shall be such as to comply with the minimum lot areas specified in the Zoning Chapter. B. Side lines of lots shall be substantially at right angles to straight street lines or radial to curved street lines. c. In the subdividing of any land, due regard shall be shown for all natural features, such as tree growth, wetlands, steep slopes, watercourse, historic spots, or similar conditions, and plans adjusted to preserve those which will add attractiveness, safety and stability to the proposed development. D. All remnants of lots below minimum size left over after subdividing. of a larger tract must be added to adjacent lots rather than allowed to remain as unusable parcels. E. Double frontage (lots with frontage on two parallel streets) or reverse frontage shall not be permitted except: 1. Where lots back on an arterial or collector street, in which case vehicular and pedestrian access between the lots and arterial streets shall be prohibited. Such double frontage lots shall have an additional depth of at least 20 feet in order to allow space for screen planting along the back lot line. 2. Where topographic or other conditions render subdividing otherwise unreasonable, such double frontage lots shall have an additional depth of at least 20 feet in order to allow space for screen planting along the back lot line. F. All lots must abut their full frontage on a publicly dedicated street. G. Rural service lots shall be designed in such a manner whereby septic tanks, drainfields and homes are located as to allow future subdivision of the land upon the requirement of the City Engineer where future urban service City of Shakopee Design Criteria Page 22 expansion is probable. The City may also require at the time of final subdivision approval that a covenant be recorded which requires the placement of future structures in accordance with approved preliminary plat design. Whenever a parcel of land is subdivided into lots containing one or more acres and there are indications that such lots may eventually be subdivided into smaller plats, the Council may require that such parcel of land be divided so as to allow for the future construction of streets and the extension of adjacent streets. Easements providing for the future opening and extension of such streets may be made a requirement of the plat. H. All lots or parcels shall have direct adequate physical access for emergency vehicles along the frontage of the lot or parcel from a public roadway 4. Bufferin2 Residential Subdivision Adjacent to Intermediate and Principal Arterial Roads A. In all residentially zoned areas determined by the Administrator to have significant noise impact within 125 feet of the roadway right-of-way or areas of noise impact estimated to maintain ambient decibel ratings of 70 DbA or greater, one or a combination of the following design. requirements shall apply: 1. Lots adjacent to the roadway right-of-way shall be sized wherein a 125 foot buffer strip be provided as additional setback to lot depth or width standards supplementary to the minimum lot size and setback of the zoning provisions of the applicable district. An earth berm or other acceptable barrier technique shall be constructed to abate noise impact adjacent to roadway right-of-way equal to or below the 70 DbA standard accompanied by the following: a. A plan showing the existing and anticipated noise levels in DbA that are or will be expected on the site and in the immediate vicinity of the site. b. A description of the site plan construction techniques, architectural designs, and other measures expected to be taken to reduce ambient noise levels. Such description shall include sufficient plans and other drawings to enable the City to accurately identify the noise reduction measures expected to be taken. B. Responsibility for any noise mitigation measures shall be the responsibility of the developer, its successors and/or assigns. This responsibility shall be City of Shakopee Design Criteria Page 23 included and clearlv stated in plat approval resolutions or other relevant approval documents. Prior to appro'ling II preliminary plan as required by this Chapter, the City shall determine that tho noise lovels will bo successfully reduced to meet the ambient 70 DbA standard. (Ord. 58, May 7, 1981; Ord. 233, December 10, 1987; Ord. 216, June 17, 1988; Ord. 287, January 16, 1990; Ord. 302, January 25, 1991; Ord. 338; "A..Ugust 6, 1992) Buffering Residential Dwellines Adiacent to Wetlands and Stormwater Ponds In all zoned areas where residential dwellings are adj acent to, or are within 100 feet of a wetland or stormwater pond, the following design requirements shall apply: A. All residential dwellings shall be at least -M- 30 feet horizontal from the 100- year high water level of the wetland or pond. B. In commercial or industrial zoned areas where a stormwater pond is proposed to be within 100 feet of a residential. dwelling, a fence shall be installed along the property line separating the commercial zoned (or industrial zoned) area and the residential property. Sect. 11 - Plan Standards 1. GENERAL PLAN AND DRAFTING REQUIREMENTS A. Title Sheet The title sheet shall include a proiect location map and an approval block for the City Engineer. B. Overall Plan Incorporated in the set of plans shall be an overall plan duplicating the entire proiect showing all proposed improvements with corresponding sheet numbers on each separate sheet and index. An approval block for Shakopee Public Utilities Commission shall be included on the overall plan sheet. c. Standard Sheet All drawings shall be submitted on standard sheets at standard scale. Standard Sheet: . Grading Plan - 22" x 34" City of Shakopee Design Criteria Page 24 . Street and Utility Plan - 22" x 34" Standard Scale: . Horizontal 1" = 50' . Vertical I" = 5' D. Plan North arrow, rights-of-way and width, property lines, lot and block numbers, street names, utility lines and size, railroad track, ditches, easements and width, match lines and reference sheet numbers shall be shown on all plan sheets. All roadway improvements and utilities shall be tied to the centerline of City right-of-way, to the centerline of a City easement, to subdivision comers, to Government land comers or to Government land lines. E. Profile To be located directly below the plan with stationing aligned as closely as practical. Original ground (dashed) and proposed if different (solid). Profile shall locate and describe additional information required under the standards for the particular improvement proposed. All utilities shall be shown in profile to include sanitary sewer, watermain, storm sewer and storm sewer crossings. F. Additional Sheets Use standard sheet with appropriate scale for details of anything not covered by City of Shakopee Standard Detail Plates or approved Mn/DOT Standard Plates. More than one (1) sheet may be used if necessary. G. Benchmark Description on each sheet, elevation, USGS 1929 datum, tie to City bench loop, description of City benchmark to which it is tied. H. Title Block Shall include the name ofproiect, subdivision or planned building group or street, as applicable and type of utility or roadway and the name, address, zip, telephone of the Engineer and developer. I. Certification City of Shakopee Design Criteria Page 25 Certification signature and registration number of Professional Engineer on each sheet. J. Required Notes These notes shall appear on the cover sheet. If no cover sheet. they shall be put on every sheet submitted for approval. 2. RECORD PLAN REQUIREMENTS All record plans shall be mylar sepias from inked and clearly legible drawings. Electronic copies ofthe record plans shall also be provided. A. Sanitary Sewer Services Stationing of sanitary sewer wyes shall be indicated. All sanitary services shall be shown onthe record plan with length. size. elevation. and pipe type noted. Indicate ifiacked. If sanitary sewer wve only is constructed. it shall be noted as "Wye Only" after the stationing. The approximate invert elevation at the 45 degree bend of all sanitary sewer service stubs shall be shown on the plans. If deep risers are placed. the height of each shall be indicated on the plans and each shall be drawn on the profile. and the height ofthe risers indicated. B. Water Services Stationing of water corporation cock shall be indicated. All water services shall be shown with length. size and pipe tyPe noted. Indicate ifiacked. All curb stop boxes shall be tied at the property line with at least two ties using the following priority: . Sanitary sewer manholes . Hydrants . Storm sewer manholes . Catch basins . Power transformers . Building corners City of Shakopee Design Criteria Page 26 c. Watermain Fittings All water fittings should be labeled as to size and type such as bends, ties, plugs, etc. D. Gate Valves All gate valves shall be tied with at least two ties using the following priority: . Fire hydrants. . Manholes. . Catch basins, if curb and gutter is in. . Buildings or other permanent structures. . Telephone pedestals. . Power poles, trees, other semi-r>ermanent items. . Stationing from hydrants, manholes, catch basins, if over 100'. . All ties should be less than 200' whenever possible. E. Fire Hydrants All fire hydrants shall have a benchmark elevation shown for the top-nut of the fire hydrant. F. All structures shall have the top of casting elevation and invert elevations shown. G. Streets City of Shakopee Design Criteria Page 27 Street as-builts would include a tyPical street section and horizontal and vertical curve data. H. Miscellaneous MiscellaneousMiscellaneousMiscellaneousMiscellaneousMiscella neousThe following information shall be shown on every sheet: . Contractor's name . Construction observer's name . Proiect engineer's name City of Shakopee Design Criteria Page 28