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Home My WebLink About#17 - Engineering Design Standards Manual Update STAFF REPORT DATE: September 17, 2019 REGULAR AGENDA ITEM: Approve Engineering Design and Construction Standards Manual – APRIL 2019 Revisions SUBMITTED BY: Jack Griffin, City Engineer REVIEWED BY: Kristina Handt, City Administrator Ken Roberts, Planning Director Marty Powers, Public Works Director Chad Isakson, Assistant City Engineer ISSUE BEFORE COUNCIL: Should the City Council approve the Engineering Design and Construction Standards Manual as revised APRIL 2019? BACKGROUND: The City maintains engineering design standards, standard specifications, and standard details for public infrastructure within the City, including streets, sanitary sewer, watermain, storm water facilities, right-of-way management and boulevard layout. T his information is compiled into an Engineering Design and Construction Standards Manual for use by staff and the development community. The latest version of the Manual is dated March 2017. The standards have been established to set minimum requirements to be met for all public infrastructure projects in the City with the intent of constructing consistent and compatible infrastructure systems throughout the community; to clearly communicate with the development community these minimum expectations and requirements; and to expedite plan design, preparation and City plan review and approvals. The engineering design standards and guidelines have been established to address the most common project elements and are to be used in conjunction with the requirements set forth by applicable codes, laws and ordinances, recognized industry standards, good engineering practice and specific project needs. Omission of reference in these standards and guidelines does not relieve responsibility for compliance with these requirements. In addition, the provisions of these standards and guidelines are not intended to prohibit the use of alternative systems, methods or components. Professional engineering judgement and ingenuity is encouraged to adapt to specific project needs. However, varying from the standards and guidelines will only be permitted with the approval of the City, after performing due diligence to ensure the design is equivalent or superior to the prescribed elements of the guideline. PROPOSAL DETAILS/ANALYSIS: The Engineering Design and Construction Standards Manual is a living document that is reviewed and modified from time to time by City staff to adapt pro-actively to changing conditions so as to remain current, address best practices and extract additional economic value and performance as needed. Changes are often based on recommendations from Engineering, Planning, Public Works, the construction observation staff or other City staff, the development community, and other stakeholders. Changes made by the City Engineer over time are periodically brought forward as revisions to the Engineering Design and Construction Standards Manual to formalize the City’s approval. The Engineering Design and Construction Standards Manual dated APRIL 2019 includes the following revisions and updates: 1. Revised minimum street widths as detailed in the attached Engineering Design Standard red lines. Street width revisions were made per Council direction following the June 11, 2019 workshop. 2. Reconciled minor street geometric parameters. o Removed tangent requirement between curves along local streets. o Reduced the minimum intersection offset distance from 150 feet to 125 feet. o Increased the minimum gutter grade in cul-de-sacs from 0.5% to 1.0%. 3. Revised the bituminous wear course mix to require a higher-grade oil in the mix (Asphalt Grade C) and eliminated the practice of “saw and seal” on local streets. 4. Increased the minimum pavement section for collector streets to require 24-inches of select granular borrow. 5. Revised the concrete strength requirements from 3,900 PSI to 4,500 PSI, consistent with the new MnDOT and industry standards. 6. Revised the minimum right-of-way widths and minimum boulevards to be consistent with the approved 2040 Comprehensive Plan, Transportation Chapter and to accommodate the wider streets. 7. Revised the City standard street light fixture and pole to reflect the City’s recent change to LED lighting. 8. Added minimum utility easement width requirements for watermain, sanitary sewer and storm sewer to be consistent with existing practices. 9. Removed the requirement to have storm water facility Outlots dedicated to City ownership. The new practice will be to require drainage and utility easements over the entire Outlot. 10. Revised the Standard Detail Plates for pedestrian ramps to be consistent with the new MnDOT and ADA standards. 11. Updated the Specifications and Details to reflect MnDOT 2018 Specification updates (updated from MnDOT 2014). 12. Updated the specifications to require storm sewer televising, simila r to sanitary sewer televising. 13. Reviewed and red lined the City Subdivision Ordinance, Open Space Ordinance, and Stormwater Management Ordinance design standards to be consistent with the Engineering Design Standards Manual. The proposed revisions were presented to the Planning Commission on August 26, 2019 and were recommended for approval as presented. FISCAL IMPACT: No fiscal impact at this time. Should the City council adopt wider street widths, the future infrastructure street and storm water construction, reconstruction and ongoing maintenance costs will increase accordingly. RECOMMENDATION: Staff is recommending that the City Council approve the Engineering Design and Construction Standards Manual as revised APRIL 2019. The recommended motion for this action is as follows: “Move to approve Resolution No. 2019-068 thereby approving the Engineering Design and Construction Standards Manual as revised APRIL 2019.” ATTACHMENTS: 1. Resolution Approving the Engineering Design and Construction Standards Manual revised APRIL 2019. 2. Engineering Design Standard Updates for APRIL 2019 (red lined version). *The full Engineering Design and Construction Standards Manual, dated APRIL 2019 is available for review at City Hall. 1 CITY OF LAKE ELMO WASHINGTON COUNTY STATE OF MINNESOTA RESOLUTION NO. 2019-068 A RESOLUTION ADOPTING THE ENGINEERING DESIGN AND CONSTRUCTION STANDARDS MANUAL REVISED APRIL 2019 WHEREAS, the City of Lake Elmo, Minnesota has prepared engineering design standards, standard specifications, and standard details for public infrastructure within the city; and, WHEREAS, the city has compiled this information into an Engineering Design and Construction Standards Manual; and, WHEREAS, this Manual will serve as the engineering standards and guidelines for the design and construction requirements for public infrastructure within the City of Lake Elmo, including streets, sanitary sewer, watermain, storm water facilities, right-of-way and boulevard layout; and, WHEREAS, the standards are established to set minimum requirements to be met for all public infrastructure projects in the city in the spirit of promoting consistent infrastructure systems throughout the community; to clearly communicate with the development community these minimum expectations and requirements; and to expedite plan design, preparation and city plan review and approvals; and, WHEREAS, the standards are not intended to be all inclusive and shall be used as a design guide, thereby allowing exceptions to these standards to be considered on a case by case basis when deemed appropriate for a specific application. NOW, THEREFORE, BE IT RESOLVED, That the City Council of the City of Lake Elmo shall adopt the Engineering Design and Construction Standards Manual revised APRIL 2019. ADOPTED BY THE LAKE ELMO CITY COUNCIL ON THE SEVENTEENTH DAY OF SEPTEMBER, 2019. CITY OF LAKE ELMO By: __________________________ Mike Pearson (Seal) Mayor ATTEST: ________________________________ Julie Johnson City Clerk CITY OF LAKE ELMO, MN | DESIGN STANDARDS MANUAL REVISION DATE: APRIL 2019 PAGE 1 of 9 ENGINEERING DESIGN STANDARDS for CITY OF LAKE ELMO STREET DESIGN AND GEOMETRICS  Minimum Street Widths, Measured from Face of Curb to Face of Curb (F‐F) ‐Standard Local Residential Street (with parking allowed on both sides)…………………….…32‐feet F‐F ‐Standard Local Residential Street, one‐way lanes with center median………….........…19‐feet F‐F ‐Standard High Density Local Residential Street (with parking allowed on both sides)…..36‐feet F‐F ‐Collector and Neighborhood Collector……………………………..Varies as Street Determined by City ‐Local Residential Street with parking on one side (when allowed by City)………………….28‐feet F‐F ‐Local Residential Street with no parking on either side (when allowed by City)……...….22‐feet F‐F  Geometric Design, Local Residential Street ‐Minimum Street Width (B‐B), parking both sides…………………………………………………...….…28‐feet ‐Minimum Street Width (B‐B), parking one side (when allowed by City)…..……………..….…24‐feet ‐Minimum Street Width (B‐B), no parking (when allowed by City)……….……………………..…22‐feet ‐Minimum Street Width, one‐way lanes with center median…………….…………………………..19‐feet ‐Center Crown……………………………………………………………………………………………………………………2.5% ‐Minimum Longitudinal Grade……………………………………………………………………........................0.5% ‐Maximum Longitudinal Grade……………………………………………………………………………………………..8% ‐Maximum Intersection Approach Grade, First 50‐feet from curb line…….…………..…………….2.5% ‐Minimum Vertical Curve Length, Crest (including stop conditions).………………………….………K=19 ‐Minimum Vertical Curve Length, Sag (including stop conditions)………………………………..……K=37 ‐Minimum Horizontal Curve Radius………………………………………………………..………............….90‐feet ‐Intersection Angles………………………………………………………………………………………………...90 degrees ‐Tangent Length at Intersection from Curb Line, Local Streets…………………………………..…..50 feet ‐Tangent Length at Intersection from Curb Line, Higher Class Streets…….......................100 feet ‐Tangent Minimum between curves……………………………………………………………………..……….50 feet ‐Minimum Intersecting Street Offset, from Centerlines…………………………………………125150‐feet ‐Curb Radius, Minimum Local to Local…………………………………………………………………….…….20‐feet ‐Curb Radius, Minimum Local to Collector…………………………………………………………………....25‐feet ‐Minimum Diameter of Cul‐de‐sac……………………………….………………………………………………..90‐feet ‐Minimum Grade around Cul‐de‐sac…………………….....................................................…1.0% 0.5% ‐Maximum Cul‐de‐sac Street Length (lots less than 2.5 acres)………………………................600‐feet ‐Maximum Cul‐de‐sac Street Length (lots equal or greater than 2.5 acres)……………....1,320‐feet ‐Temporary Cul‐de‐sac at plat line……………………………………………………………………….……..Required  Geometric Design, Collector Street ‐Design Standards………………………………………………Meeting State‐Aid for minimum design speed ‐Minimum Street Width, back of curb to back of curb…………..……Varies (as determined by City) ‐Maximum Longitudinal Grade…………………………………………………………………………………………..…6% ‐Intersection Angles………………………………………………………………………………………………...90 degrees ‐Tangent Length at Intersection from Curb Line……………………………………….....................100 feet ‐Tangent Minimum between curves……………………………………………………………………..……….50 feet CITY OF LAKE ELMO, MN | DESIGN STANDARDS MANUAL REVISION DATE: APRIL 2019 PAGE 2 of 9 ‐Minimum Vertical Curve Length, Sag and Crest………………State‐Aid for minimum design speed ‐Minimum Horizontal Curve Radius………………………………….State‐Aid for minimum design speed ‐Minimum Intersecting Street Offset, if allowed, from Centerlines……..……..……………….250‐feet ‐Street/Roadway Access………………………………..Per City Access Management Spacing Guidelines ‐Driveway Access, Residential……………………….…………………………………………….…………...Prohibited ‐Driveway Access, Commercial…………….………..Per City Access Management Spacing Guidelines ‐Curb Radius....………………………………………………………………………………………………………….…..25‐feet  Pavement Section Design (Pavement sections below are minimum allowed. Additional pavement section may be required based on Geotechnical Report of the subgrade soils). ‐Local Residential Street……………………………………………………………………….Minimum 7‐Ton Design ‐Subbase, Select Granular Borrow (SPEC 3149.2B)…….………………………….……Minimum 12‐inches ‐Subsurface Drainage System…………………………………………………………………………………..….Required ‐Base, Aggregate Base, Cl. 6 100% Crushed Stone Aggregate (SPEC 3138).…..Minimum 6‐inches  Note: Class 6 Recycled Material Substitute by City Engineer Approval ‐Non‐Wearing Course, MnDOT 2360 Type SP 12.5, Mixture 2B, Asphalt Grade C..……..2‐inches ‐Wearing Course, MnDOT 2360 Type SP 9.5, Mixture 2B, Asphalt Grade C….…………….1½‐inches ‐Collector Street and Above…………………………………………………………….….Minimum 10‐Ton Design ‐Subbase, Select Granular Borrow (SPEC 3149.2B)……….………………….……Minimum 24 12‐inches ‐Subsurface Drainage System…………………………………………………………………………………..….Required ‐Base, Aggregate Base, Cl. 6 100% Crushed Stone Aggregate..……………………..Minimum 8‐inches  Note: Class 6 Recycled Material Substitute by City Engineer Approval ‐Non‐Wearing Course, MnDOT 2360 Type SP 12.5, Mixture 3C….……….…..…………………..2‐inches ‐Wearing Course, MnDOT 2360 Type SP 9.5, Mixture 3C..……………………..…………………….2‐inches  Draintile/Street Subsurface Drainage ‐Type……………………………………………………………………………………….……Sch. 40 Rigid PVC Perforated ‐Size……………………………………………………………………………………………………………………………..….4‐inch ‐Sock……………………………………………………………………………………………………….……MnDOT SPEC 3733 ‐Location…...All Low Points in both directions; at 350 foot intervals, and Project Specific Design ‐Length……………………………Minimum 100‐foot runs; 100 feet in both directions from low points ‐Clean Outs…………………………………………………………………………Every 150 feet and at all dead ends  Curb and Gutter ‐Material, All Purposes………………………………………………………………………………………..………Concrete ‐Strength, Minimum Requirements…………………….…………………………………..…….…4,500 3,900 PSI ‐Type: New Developments, Single Family Residential……………………………………….…Surmountable ‐Type: Multifamily, Commercial, Collector Roads, Medians, Reconstruction………………….….B618  Utility Conduit ‐Type……………………………………………………………………………………….………………….….PVC Schedule 40 ‐Location/Depth……………..Perpendicular to Street and minimum 1‐foot below Street Subgrade  Entrances/Driveways ‐Maximum Driveway Width at Right‐of‐way…………………………………..……Varies by Zoning District ‐Bituminous Driveway Minimum Thickness, Section…………………………………..…………Match Street ‐Residential Concrete Driveway Minimum Thickness……………………………………………………6‐inches ‐Commercial Concrete Driveway Minimum Thickness………………………………………..………..8‐inches CITY OF LAKE ELMO, MN | DESIGN STANDARDS MANUAL REVISION DATE: APRIL 2019 PAGE 3 of 9  Signing ‐Design Standards………………………………………………………………………………………………………MMUTCD ‐Sheathing Type……………………………………………………………………….…Type IX Diamond Grade (DG3) ‐Sign Posts……………………………………………………………………..………Pre‐punched 14 ga. Square Tube RIGHT‐OF‐WAY AND BOULEVARD LAYOUT  Minimum Right‐of‐way Widths ‐Principal Arterial……………………………………………………………………………………….150 feet to 300 feet ‐Intermediate Arterial………………………………………………………………………………..100 feet to 300 feet ‐Minor Arterial…………………………………………………………………………………………..120 feet to 150 feet ‐Collector Street…………………………………………………………………………………………100 feet to 150 feet ‐Commercial or Industrial Service Street………………………………………………………………………..80 feet ‐Standard High Density Local Residential Street (36‐feet with parking on both sides)………...70‐feet ‐Standard Local Residential Street (32‐feet with parking on both sides)……………..……...…...…66‐feet ‐Local Residential Street with parking on one side (when allowed by City)…………………….….60‐feet ‐Local Residential Street with no parking on either side (when allowed by City)…………...….60‐feet ‐Marginal Access Street (with no trail or sidewalk)…………………………………………………………….50 feet ‐Cul‐de‐Sac……………………………………………………………………..60 feet; turn‐around radius of 60 feet  Right of Way Widths ‐Local Residential Street Minimum Width………………………………………..……………………………60‐feet ‐Cul‐de‐sacs……………….…………………………………………………………………………………..…..60‐foot radius ‐Collector Street Minimum Width…………………………..…………...…...Varies (as determined by City)  Boulevard, Local Residential Street ‐Width…………………………………………………………………………...…15.5 16‐feet (15‐feet at cul‐de‐sacs) ‐Slope, Typical and Maximum………………………………………………………………..………………..4% and 4:1 ‐Topsoil Minimum……………………………………………………………………………………..…………………….6‐inch ‐Turf Treatment…………………………………………………………………………………………………..……..Lawn Sod ‐Tree Location without Sidewalk or Trail……………………….................................8‐feet back of curb ‐Tree Location with Sidewalk or Trail…………………………………………….…..…………5‐feet back of curb ‐Street Light Location……………………………………………………………………………………5‐feet back of curb ‐Street Light Fixture………………………………..Traditional Colonial LED, Type B 4000 Lumens (Black) ‐Street Light Pole……………………………………………..…15‐foot Washington Fluted Aluminum (Black) ‐Street Light Type/Pole…………..……………….15‐foot California Acorn w/Aluminum Pole (All Black) ‐Hydrant Location………………………………………………………………………………….……..5‐feet back of curb  Sidewalks ‐Collector Street…………………………….……………………………..………………...……Required on both sides ‐Local Residential Street…………………………….……………………………...……….……Required on one side ‐Cul‐de‐sac Street…………….………….……………………………….………………Required for trail connection ‐Width……………………………………………………………………………………………………...…………………..…6‐feet ‐Sidewalk Maximum Longitudinal Grade……………………………………………………………………………….6% ‐Pavement Section…………..…………………………………..………5‐inch Concrete; 4‐inch Select Granular  Trails CITY OF LAKE ELMO, MN | DESIGN STANDARDS MANUAL REVISION DATE: APRIL 2019 PAGE 4 of 9 ‐Locations…………………………………..……………………………..……....…Per City trail plan and as directed ‐Width, Local Trail……………….………………………………………………………………..………………………...8‐feet ‐Pavement Section, Local Trail…………..………………2.25‐inch Bituminous; 8‐inch minimum Class 5 ‐Maximum Longitudinal Grade……………………………………………………………………………………………..8%  Berm Construction in Boulevard ‐Maximum Side Slope with Maintenance Requirements…………………………………………………......3:1 ‐Maximum Side Slope with Natural Vegetation………………........................................................2:1 CITY OF LAKE ELMO, MN | DESIGN STANDARDS MANUAL REVISION DATE: APRIL 2019 PAGE 5 of 9 SANITARY SEWER  Force Main ‐Material……………………………………………………………………………………………………….……...PVC or HDPE ‐PVC, 2‐inch–24‐inch……….……………………………………………………………………………………… C900/C905 ‐HDPE Class, 1‐inch…………………………………………………………………….…………………………………….SDR 9 ‐HDPE Class, 2‐inch–24‐inch……………………………………………………….……………………………..…..SDR 11 ‐Minimum Cover……………………………………………………………………………………………………..……7.5‐Feet ‐Location of main in Street……………………………………………………………………….……….Project Specific ‐Tracer Wire………………………………………………………….….12 AWG solid, PRO‐TRACE HDD‐CCS PE45 ‐Air Relief Valve and Manhole Locations………………………………………………….………….All High Points ‐Clean Outs………………………………………………………………………………………………………….All Low Points  Gravity main ‐Material…………………………………………………………………………………………………………….……………….PVC ‐Minimum Diameter……………………………………………………………………………………..………………...8‐inch ‐Class, up to 20‐feet in depth………………………………………………………………………..………………..SDR 35 ‐Class, 20‐25 feet in depth……………………………………………………………………………………….……..SDR 26 ‐Class and Material, over 25 feet in depth………………………………………………………...Project Specific ‐Minimum cover over pipe……………………………………………………………………………………………5.5‐feet ‐Maximum depth of pipe……………………………………………………………………………………………….30‐feet ‐Slope……………………………………………………………………………………………..………..Ten States Standards ‐Tracer Wire…………………………………………………………………12 AWG solid, PRO‐TRACE HF‐CCS PE45 ‐Location of main in Street………………………………………………………………………………………..Centerline  Sanitary Sewer Manholes ‐Type………………………………………………………………………………….……………………….....Precast Concrete ‐Maximum inlet/outlet elevation difference…………………………………………………………………...2‐feet ‐Minimum depth of Manhole…………………………………………………………………….…………………….6‐feet ‐Type of Casting………………………………………………………………………………………………….……….R‐1642‐B ‐Joints and Assembly……………………………………………………………………………….………..Per City Details ‐Location………………………………………………………………………………………………..……….Street Centerline ‐Maximum Spacing………………………………………………………………………………………………..…….400‐feet ‐Flow Line Match Required……………………………………………………………………………………8/10ths Rule ‐Drop Across All Manholes Required………………………………………………………………………..……0.1‐feet ‐Connections to Existing Manholes………………………………………………………….….Core Drill with Boot ‐Outside drop minimum…………………………………………………………………………………………………..2‐feet ‐Outside drop Material….………………………………………………………………………………………..Ductile Iron  Service Pipe ‐Material and Class……………………..………………………………………………….…………….PVC SCHEDULE 40 ‐Minimum Diameter…………………………………………………………………………………………………….....4‐inch ‐Tracer Wire…………………………………………………………………12 AWG solid, PRO‐TRACE HF‐CCS PE45 ‐Drive‐In Magnesium Grounding Anode Rod……………........Copperhead Part # ANO‐1005 (1.5lb)  Easements ‐Sanitary sewer pipe and structures require minimum 30‐foot easements centered over the pipe/structure if not located within the public right‐of‐way. Additional easement width may be required as determined by the City Engineer and Public Works Director. Easements must be dedicated to the City and be provided in the City’s standard form of easement agreement. CITY OF LAKE ELMO, MN | DESIGN STANDARDS MANUAL REVISION DATE: APRIL 2019 PAGE 6 of 9 WATERMAIN  Water Service Pressures ‐Individual Booster Pumps required………………………………………………..……….development specific  Main Pipe ‐Material……………………………………………………………………………………………………….……………………..DIP ‐Class……………………………………………………………………………………………………………….………………CL. 52 ‐Minimum Diameter – Mainline………..………………………………………………………….………………...8‐inch ‐Minimum Diameter – As allowed by City Engineer..…………………….………………………..……….6‐inch ‐Minimum Diameter – Hydrant Lead……………………..……………………..………………………..……….6‐inch ‐Minimum Cover…….…………………………………………………………………………………………..…………7½‐feet ‐Maximum Length of Dead Ends…………………………………………………………………..…………1,000‐feet ‐Air Release measures…………………………………………………………………………….…………….MH, Hydrant ‐Tracer Wire…………………………………………………………………12 AWG solid, PRO‐TRACE HF‐CCS PE45 ‐Location of main in Street……………….……………………………………………………………..….North or West  Hydrants ‐Type……………………………………………………………………………………….……...…...Waterous Pacer WB‐67 ‐Depth of Bury…………………………...………………………………………………………………………………….8½‐feet ‐Maximum Coverage Radius, Residential..……….……………………………………………………..……500‐feet ‐Maximum Coverage Radius, Commercial…………….………………………………………………..……300‐feet ‐Gate valve on Hydrant leads…………………………………………………………………………..…………………..Yes ‐Hydrant Nozzle………..…………………………………………………4‐inch Storz with Pentagon Nut end cap ‐Temporary dead end lines…………………………………….………Hydrant required (no air bleed valves)  Valves ‐Resilient Seat Gate Valve, for 12‐inch pipe & smaller…..……American Flow Control 2500 Series ‐Butterfly Valve, for pipe over 12‐inch………………………………….…..…………………Mueller Lineseal III ‐Valve Box………………………………………………...........................................................Tyler G‐Box6860 ‐Maximum area isolated by valving………………………………………………………………………….20 services ‐Maximum distance between valves on Trunk Mains……………………………………………….….800‐feet  Service Pipe ‐Service Material…………………………………………………………………………….……………….Type “K” copper ‐Corporation Stop…………………………..…………………………………………….……….A.Y. McDonald 74701B ‐Curb Stop ………….…………………………………………………………………………………..A.Y. McDonald 76104 ‐Curb Box …………………………………………………………………...A.Y. McDonald 5614 w/rod & Mpls. top  Easements ‐Watermain lines and hydrants require minimum 30‐foot easements centered over the pipe if not located within the public right‐of‐way. Additional easement width may be required as determined by the City Engineer and Public Works Director. Easements must be dedicated to the City and be provided in the City’s standard form of easement agreement. CITY OF LAKE ELMO, MN | DESIGN STANDARDS MANUAL REVISION DATE: APRIL 2019 PAGE 7 of 9 STORM SEWER  Design ‐Design Frequency for Storm Sewer……………………………………………………….…...………………..10‐year ‐Minimum storm sewer design velocity…………………………………………………………….………….……3‐fps ‐Maximum storm sewer design velocity…………………………………………………………………………..15‐fps ‐Maximum storm sewer outlet velocity…………….………………………………………………………….……5‐fps ‐Minimum Outfall Pipe Slope……….……….Verify positive grade at completion (no reverse grade)  Main Pipe ‐Storm Sewer Pipe Material…………………………………………………………………………………………….….RCP ‐Minimum Cover Depth…………………………………………………………………………………………………...3‐feet ‐Minimum Pipe Diameter, Main…………………………………………………………………………………....15‐inch ‐Minimum Catch Basin Lead…………………………………………………………………………………………..12‐inch ‐Location of main in Street……………………………………………………………..…………………….South or East  Culvert pipe ‐Culvert Material, urban road or crossing public road……….…………………………………………….….RCP ‐Culvert Material, rural road private driveway….……………….……………………………………………...CMP ‐Minimum Culvert Size……………………………………………………………………………………………….....15‐inch ‐Apron and Trash Guard Required……………………………………………………………………………….……...Yes  Manholes ‐Type………………………………………………………………………………………………………………Precast Concrete ‐Sump Depth and Location………………………….....4‐feet, located at street prior to discharge point ‐Minimum Structure Depth………………………………………………………………………………………........4‐feet ‐Casting…………..……………………………………………………………………………………………………..…..R‐1642‐B ‐Minimum Adjustment Rings…………………………………………………………………………………….…………….2 ‐Maximum Adjustment Rings…………………………………………………………………………………..……...1‐foot  Catch Basins ‐Type………………………………………………………………………………………………………..…….Precast Concrete ‐Minimum Structure Depth…………………………..…………………………………………….……………........4‐feet ‐Maximum run to Catch Basin………………………………………………………………….…………………..350‐feet ‐Casting, Curb & Gutter, B Style Curb………………….………………………………………………………..R‐3067V ‐Casting, Area Drain……………………………………………………………………..…………………………………R‐4342  Easements ‐Storm sewer pipe, structures and flared end sections require minimum 30‐foot easements centered over the pipe/structure if not located within the public right‐of‐way. Additional easement width may be required as determined by the City Engineer and Public Works Director. Easements must be dedicated to the City and be provided in the City’s standard form of easement agreement. CITY OF LAKE ELMO, MN | DESIGN STANDARDS MANUAL REVISION DATE: APRIL 2019 PAGE 8 of 9 STORMWATER MANAGEMENT AND STORMWATER BMPs Note: Stormwater facilities shall be in accordance with the requirements listed herein; in accordance with the requirements of the applicable watershed district; and in accordance with the Minnesota Pollution Control Agency NPDES Construction Storm Water Permit. In addition, all “Recommended” and “Highly Recommended” provisions of the Minnesota Stormwater Manual should be considered requirements by the City of Lake Elmo unless specifically approved otherwise by the City Engineer.  Site Design ‐Facility locations….…………………………………….……….……………….Located in Outlots deeded to City ‐Location and Size………………..……………………………………………………………..……above 100‐year HWL ‐Building Lowest Floor above 100‐year HWL…………………………………………………………………….2‐feet ‐Building Lowest Opening above EOF…………………………………………………………………………….…1‐foot ‐Minimum access road width (located in Outlot)…………………………………………………………...20‐feet ‐Maximum grade for maintenance access roads………………………………………………………………...10% ‐Setback from building foundations……………………………………………………………………………….35‐feet ‐Flood Protection…….……………Overland Emergency Overflows Required (No landlocked basins)  Stormwater Ponds (Detention Basins) ‐Design Frequency (DF)………………………….…2, 10, and 100‐year, and 100‐year 10‐day snowmelt ‐Minimum Basin Depth to HWL.……………………………………………………………………………………….3‐feet ‐Maximum Pond Depth to HWL…………………….………………………………………………………..……..10‐feet ‐Average Permanent Pool Depth………………………………..........................................4‐feet to 6‐feet ‐Permanent Pool Length‐to‐Width Ratio………………………………………………………….....3:1 or greater ‐Maintenance Bench Maximum side slope, first ten feet above Permanent Pool….………..….10:1 ‐Aquatic Bench Maximum side slope, first ten feet into Permanent Pool….…………………...….10:1 ‐Maximum side slope, beyond first ten feet…………….…………………………………..………………………3:1 ‐Pretreatment Sediment Forebay……………………………………………….…………………….10% Pond Area ‐Required freeboard……………………………………………………………………………………..2‐feet above HWL ‐Pond Liner…………………………………………………………………………Clay lined per VBWD specifications  Drainage Swales ‐Maximum side slopes on Swales (maximum slopes allowed only when necessary)……….......3:1 ‐Maximum side slopes on Right‐of‐Way Swales……………………………………………………….…………..4:1 ‐Minimum longitudinal Swale grade…………………………………………………………………………..…........2% ‐Minimum Swale depth within Right‐of‐Way…………………………………………………..………...18‐inches ‐Minimum Bottom Width………………………………………………………………………………………………...4‐feet  Infiltration Facilities (Bioretention Areas and Rain Gardens) ‐Inlet control from Streets………….…Use Neenah R‐3067‐V casting on Catch Basin (no curb cuts) ‐Maintenance Agreement for public right‐of‐way..……………………………………………………..Required ‐Maintenance Access Easement..………………………………………………………………………………..Required ‐Minimum distance from septic system or drainfield………………………………………………….....35‐feet ‐Minimum distance from public or private well.…………………………..…………………………….....50‐feet ‐Maximum Site Slope……………………………………………………………………………………………………………5% ‐Minimum depth to Bedrock………………………………………………………………………………………..….5‐feet ‐Minimum depth to Seasonally High Water Table…………………………………………………………...5‐feet ‐Located in “hotspot” drainage shed (i.e. gas stations)……………………………………………..Prohibited ‐Located in Hydrologic Soil Group D Soils……………………………………..…………………………..Prohibited ‐Underdrain, Group C Soils (filtration)………………..…………………….…………………………………Required CITY OF LAKE ELMO, MN | DESIGN STANDARDS MANUAL REVISION DATE: APRIL 2019 PAGE 9 of 9 ‐Soil infiltration rates………………………………………………………..*By Field Testing at Facility Location ‐Maximum side slope….……………………………………………………………………………………………………….4:1 ‐Maximum drain dry time………………………………………….………………………………………………..48 hours ‐Soil medium……………………………………….…………………….…MnDOT 3877 E Rooting Topsoil Borrow ‐Seeding…………..…………………………………………….….MnDOT 3876 Specifications with Type 33‐261 ‐Plantings………………………………………Planted in conformance with City approved landscape plan * Soil borings are required to verify infiltration rates. Borings must be taken to a depth of 5 feet below proposed infiltration basin elevation.  Minimum 2 borings per facility up to 5,000 SF. of infiltration area.  Minimum 3 borings per facility up to 10,000 SF. of infiltration area.  Additional boring required for every additional 2,500 SF. of infiltration area.  Other Stormwater BMPs: The City of Lake Elmo has adopted the following additional BMPs and Low Impact Development practices for the City and promotes their use in accordance with these Engineering Design Standards and the applicable City Code.  Open Space Developments in applicable Zoning Districts.  Narrow Streets through minimized street width standards.  Stormwater Reuse.  Infiltration/filtration Practices.  Vegetated Swales (Ribbon Curbs and Curbless Streets in applicable Zoning Districts).  Temporary Erosion and Sedimentation Control using Engineering Standards Manual.  Stormwater Site Design. ‐Conservation of open spaces to protect a site’s natural areas. ‐Impervious lot coverage credits for Stormwater BMPs. ‐Use of Pervious Pavements. ‐Adoption of Minimal Impact Design Standards (MIDS) to mimic predevelopment hydrology. ‐Incorporation of Landscaping and use of Native Vegetation. DETAIL PLATE NUMBERS AND PLAN NOTES  Pipe Installation 101,103,105  Watermain 200A,201,203,204,206,207A,207B,208,210,211  Sanitary Sewer 300A,301,302,303,305,306,311,313,314,315  Storm Sewer 400A,402,404,405,406,407,408,409,410,411, 412,416,417,419,420,421  Pavements, Curbs, Walks 500A,501,502,504,505,506,507A,507B,507C, 507D,507E,507F,508,509,510,511,512,513,514  Erosion Control 600A,600B,600C,600D,601,603,604,605,606  Typical Sections and Right‐of‐Way 801,804,805,806,807A,807B  Signing/Pavement Markings/Lighting 900A,901,902,903 NOTE: Minimum and maximum design parameters identify the end range of the acceptable design in the as- built condition and therefore must account for construction tolerances. Minimum and maximum design parameters are intended for use in the unique and extreme circumstance and therefore should have limited use in the base design.