§ 159.07  DESIGN STANDARDS.
   The following design standards shall be construed as minimum requirements. More stringent standards may be applied due to the unique characteristics and circumstances of any individual subdivision, as the city unilaterally deems to be appropriate and necessary to ensure that each and every subdivision produces sound and orderly growth and improves public health, safety and welfare throughout the city.
   (A)   General requirements.
      (1)   Subdivisions and all subdivision improvements shall conform to the Comprehensive Plan; Zoning Code, Statewide Urban Design and Specifications (SUDAS) as adopted and amended by the city; Parkland Code; and all other applicable city and state regulations. All lots in proprietor’s plats shall be served by public sanitary sewers; water mains; storm sewers and other drainage improvements; streets; sidewalks and trails; parks and park infrastructure; to be designed and constructed by the developer as subdivision improvements in full accordance with this Code and particularly as set forth in this section.
      (2)   Preliminary plats shall be submitted for entire subdivisions whenever practical, and at a minimum for multiple final plat phases within boundaries as prescribed by the Engineering and Community Development Departments for parcels that are more than 100 acres in area or that have unique characteristics. By this requirement the city intends to ensure that every subdivision will, in its entirety, be optimized in all respects to protect and increase property values and public health, safety and welfare presently and in the future, particularly by optimizing vehicular and pedestrian circulation systems; the extension of infrastructure to establish connectivity at an early date, and facilitate the subdivision and development of other properties; and the locations and improvement of parks and open spaces, to efficiently serve and satisfy the needs of the subdivision and of the public as a whole.
      (3)   Subdivisions shall not endanger health, safety or general welfare of the public or of persons residing or working on nearby properties, and shall not impair an adequate supply of light and air to nearby properties.
      (4)   Subdivisions shall be designed to locate and configure subdivision improvements in a manner that will not unduly diminish or impair the use and enjoyment of nearby properties. No subdivision shall be designed or improved in a manner that impedes or appears to impede the development of nearby properties that are within the city or the designated area of review.
      (5)   Proprietors’ plats shall be improved by the developer to provide all lots within the subdivision with adequate water mains and fire hydrants, sanitary sewers, storm sewers and surface water flowage channels, and storm water detention to protect the public health, safety and welfare, and to prevent the overload of any existing public infrastructure. A developer may be required to extend or expand existing off-site public infrastructure as necessary to fully improve a proposed subdivision, or the City Council may, at its sole discretion, require a proposed subdivision to be delayed until such extension or expansion can be funded and constructed by the city or other governmental entity.
      (6)   Developers shall provide for the perpetual maintenance of any and all subdivision improvements that are not dedicated to the city or other governmental entity, by establishing an owner’s association or other person, whether an individual or individuals, in a manner and form that is acceptable to the city. Such improvements may include but are not limited to storm water detention and infiltration basins; buffer yards, landscaping, fencing or walls, and other screening; subdivision signs, directional signs, traffic signs and pavement markings; and on-site lighting.
      (7)   Every subdivision shall be designed with regard for existing and proposed topography and drainage patterns, by blending grading for the subdivision smoothly into the land forms on adjoining properties; considering and providing for drainage into and through the subdivision, both existing conditions and at full development of the drainage basin; and by controlling runoff.
      (8)   (a)   An attempt should be made to preserve mature upland forestation and other natural vegetation and geological features, while recognizing that the developer is required to substantially grade and contour a subdivision to construct the required subdivision improvements and properly grade streets, alleys, and lots to comply with this and other city codes and regulations, and state and federal regulations, and recognizing that the probability of post-development survival of trees and other existing vegetation may be greatly diminished by such necessary site modifications and disturbances.
         (b)   Where preservation does not appear to be practical, subdivision and development landscaping should select overstory tree species that will create or reestablish the dominant tree species that would be native to the environ when possible, or alternatively to create subdivision character that is in keeping with the city as a whole, or that will uniquely identify the subdivision.
   (B)   Streets. The City Engineer shall have the sole authority to establish the classification of a street as an arterial, collector or local street for the purposes of this Code.
      (1)   Connectivity and general design. Public streets in all proprietor’s plats shall be designed and configured to provide connectivity between adjoining properties and subdivisions to facilitate access and circulation within neighborhoods, to thereby minimize and reduce traffic congestion, improve the efficiency of providing municipal services and enhance public health, safety and welfare together with protecting and increasing property values. Subdivisions of large parcels shall be designed and phased accordingly, to establish such connectivity at the earliest reasonable date.
      (2)   Warranty deeds. All new street rights-of-way shall be conveyed by warranty deed and without any conditions or limitations, in accordance with the following:
         (a)   Arterial street rights-of-way shall be designed to have a total minimum right-of-way width of 120 feet, or wider if so required by the City Engineer or City Council, and subdivisions on each side of the centerlines thereof shall dedicate one-half of such width;
         (b)   Collector street rights-of-way for residential subdivisions shall be designed to have a total minimum right-of-way width of 60 feet, and local street rights-of-way for nonresidential subdivisions shall be designed to have a total minimum right-of-way width of 80 feet, or wider if so required by the City Engineer or City Council.
         (c)   Local street rights-of-way for residential subdivisions shall be designed to have a total minimum right-of-way width of 50 feet, and local street rights-of-way for nonresidential subdivisions shall be designed to have a total minimum right-of-way width of 80 feet, or wider if so required by the City Engineer or City Council.
         (d)   Additional street rights-of-way widths may be required to be dedicated at the intersections of streets and access points, in order to accommodate turn lanes and sidewalks within the rights-of-way.
      (3)   Costs; responsibilities. Developers shall be fully responsible for the entire costs of improving all collector and local streets within a subdivision, and for the costs of paving a width of not less than 15.5 feet of roadway along all arterial street frontages by providing a cash escrow to be held in a city account or by posting surety therefore, and turn lanes that serve or will serve the subdivision whether located within the subdivision or on an arterial street.
      (4)   Continuation of existing and planned streets. Subdivisions shall be designed to provide for the continuation of existing and planned public streets, and those in valid preliminary plats, in whatever manner is deemed appropriate by the City Engineer. Streets shall be designed and configured to conveniently channel local traffic onto collector and arterial streets and to discourage through traffic, being that which does not have an origin or destination within the subdivision or nearby area, from utilizing collector or local streets as a means of traveling from arterial street to arterial street.
      (5)   Right angles. Street intersections shall be at right angles wherever possible. The minimum off-set between street intersections on local and collector streets shall be 300 feet, and the minimum on an arterial street shall be 1,200 feet.
      (6)   Turnarounds; improved design. Streets that are temporary dead-ends shall be provided with a turnaround and an improved roadway of a design that is satisfactory to the City Engineer. Permanent dead-ends other than cul-de-sacs are prohibited, and no lots shall take their access from a dead-end other than a cul-de-sac, permanent or temporary.
      (7)   Improvement and dedication. Streets shall be so located and designed as to be improved and dedicated to the full rights-of-way and roadway widths as required by this Code. No street shall be designed or accepted for half-width paving or right-of-way dedication unless recommended by the Director and the City Engineer.
      (8)   Limited access to arterial streets.
         (a)   Streets and other vehicular accesses shall be designed to intersect or otherwise connect to arterial streets at points measuring not less than a nominal minimum distance of 600 feet between full movement accesses and of 300 feet between any access and right-turn only or other limited-movement accesses to said arterial street.
         (b)   Single-family lots in proprietor’s plats shall not be allowed to have vehicular access to an arterial street, except in the “A-1” Agricultural Reserve and “A-2” Estate Residential Districts where no other streets are reasonably available to provide access and subject to the locations of any such accesses being shown on the plat and approved by the City Council. Such access restriction shall be noted on the final plat.
         (c)   Hickman Road, Merle Hay Road and a portion of Douglas Avenue are controlled access streets to which access is allowed only by city ordinance in accordance with § 99.053, or by obtaining a permit from the Iowa Department of Transportation (herein “IDOT”).
      (9)   Turn lanes and traffic-control devices.
         (a)   Right and left turn lanes shall be provided at all points that provide or are intended to provide access to an arterial street from existing or proposed nonresidential or multi-family residential development, unless such requirement is waived by the City Engineer, and the City Engineer may require said turn lanes to be provided for said access to a collector street.
         (b)   The City Engineer may require traffic signalization or other traffic control devices to be included in the subdivision improvements for any proprietor’s plat that is zoned or planned for nonresidential or multi-family development.
      (10)   Shared access and alignment. Streets and other vehicular accesses shall be designed to align with existing or proposed, approved streets and other vehicular access points on the opposing frontage of arterial and collector streets. Cross-access easements shall be provided, in whatever configuration, dimension, and manner that the City Engineer deems necessary and appropriate, to allow and facilitate the sharing of access to public streets by multiple properties, whether the properties are within or outside of the subdivision boundaries, in order to reduce traffic conflicts and congestion, and improve safety.
      (11)   Cul-de-sacs.
         (a)   Cul-de-sacs shall not exceed a length of 600 feet as measured from the centerline of the intersecting street to the center of the turnaround, and shall not serve more than 40 dwelling units, unless a longer length or larger numbers of units is approved by the City Council in accordance with § 159.14.
         (b)   A permanent turn around shall be provided at the end of each cul-de-sac in accordance with SUDAS, including increased radii in nonresidential subdivisions, except that the transition radii between the cul-de-sac turnaround and approach street shall be a minimum of 92.5 feet as measured at the back of curb of the roadway, and a minimum of 80.0 feet as measured at the street right-of-way.
      (12)   Planting islands and subdivision signs.
         (a)   Cul-de-sacs may include a circular planting island having a 15-foot maximum radius; islands within roundabouts may include plantings; and medians may include plantings outside of vision clearance zones, subject to the requirements of this section; and subdivision identification signs may be installed on private property within a proprietor’s plat, all subject to an owner’s association being established by the developer to maintain such islands and signs in perpetuity.
         (b)   The plantings in any such islands and medians shall predominately be understory and overstory trees that are selected on the basis of being generally able to withstand salts, heat, dry conditions and the otherwise stressful conditions that are characteristic of such islands and medians. The islands and medians shall be mulched with rock, brick or other ground cover materials that are more or less permanent in nature, or designed to facilitate mowing and other operations if vegetative ground cover is allowed. The design of the islands, medians and subdivision signs as a whole shall be such that minimal maintenance will be required, and subject to review and approval by the Engineering and Community Development Departments.
      (13)   Gated streets and entrance drives. Gated streets and entrance drives shall be constructed with sufficient storage capacity to prevent queuing vehicles from encroaching into a public street right-of-way or from obstructing any sidewalk or bicycle trail or lane, but in all cases shall have not less than 75 feet of queuing space between the gate and said points.
      (14)   Paved. All proposed public streets shall be paved with portland cement concrete (PCC), unless the City Engineer expressly approves an alternative paving material.
(Title VII, Ch. 3, §§ 1.8.2 and 1.8.3)
   (C)   Sanitary sewers. The subdivision improvements for proprietor’s plat shall include the extension of sanitary sewers and appurtenances thereto to serve every lot within the subdivision, and to the Subdivision’s outermost boundaries as deemed necessary by the City Engineer, or the Urbandale Sanitary Sewer District or Urbandale/Windsor Heights Sewer District as the case may be for a trunk sewer, to facilitate the service and development of adjoining and nearby properties within the city and its designated area of review.
   (D)   Storm sewers, surface water flowage, stormwater detention and other stormwater management requirements. Storm sewers and appurtenances thereto shall be extended to Subdivision boundaries as deemed necessary by the City Engineer, for the purposes of both picking up and discharging runoff at the boundaries of the subdivision.
      (1)   Erosion control. Storm sewers and appurtenances thereto, drainage ways and other surface water flows, and storm water detention shall be designed in accordance with SUDAS specifications as amended and adopted by the city, and in addition thereto erosion control improvements shall be installed in and along all surface drainage channels to reduce flow velocities and protect channel bottoms and banks from scouring and cutting, and at storm sewer outfalls and discharge points, in whatever matter and extent that the City Engineer finds necessary to prevent channel and sheet erosion to a reasonable extent. Such improvements may include, but are not limited to, drop structures, check dams, placement of rip-rap and weirs.
      (2)   Footing drain sewers. All lots that are zoned or planned for single-family residential development shall be provided with a storm sewer that is capable of collecting and conveying footing drain discharges to an appropriate outlet.
      (3)   Surface flowage provisions for large-storm events. Provisions shall be made and maintained for surface passage of runoff from storms that exceed the design capacity of the storm sewer system, without causing flooding or damage to public streets or nearby properties. Surface water flowage easements shall be provided over any and all such areas of flow that convey any off-site runoff through a lot, of sufficient dimensions to cover the runoff resulting from a storm having a 1% chance of occurrence in any single year.
      (4)   Off-site discharge. If it is necessary to discharge a concentration of surface runoff onto an adjoining property, provisions shall be made to dissipate the erosive energy from said concentration of runoff and to maintain the general drainage pattern as it existed prior to construction of the Improvement.
      (5)   Storm detention.
         (a)   Storm detention shall not be located within a FEMA-designated 1% floodplain. Storm detention shall not be located within minimum required buffer yards or landscape setbacks unless the detention is located within a subsurface structure of sufficient depth below the surface to allow required landscaping to be planted and maintained over such buried detention.
         (b)   Low flows shall be piped through detention basins whenever possible, and a paved trickle channel shall be provided to convey the low flows if piping is not practical, to facilitate maintenance of the basin unless the basin is expressly designed to facilitate the absorption or infiltration of runoff storm detention.
      (6)   Subsurface drainage. Vegetated areas shall have a 2% minimum slope to maintain positive drainage throughout each lot and the subdivision as a whole. Subsurface drainage shall be provided in such locations and manner as may be required by the City Engineer, which may include but is not limited to the rear lot lines of any or all lots.
   (E)   Water mains and appurtenances.
      (1)   Water mains shall be a minimum of eight inches in diameter, or larger if increased size is determined to be necessary to provide domestic and fire flows as determined to be satisfactory and necessary by the Urbandale Water Utility. Fire hydrants shall be provided in the number and locations required by the Water Utility and Fire Department, and shall be supplied with appropriate connections as may be specified by the Water Utility and Fire Department. Developers shall be fully responsible for the costs of all mains that are 12 inches or less in diameter, together with all hydrants, valves and other appurtenances thereto, and as may be otherwise required to be in full accordance with the requirements of the Water Utility.
      (2)   No lot shall have more than one service line, whether or not in actual use, unless expressly approved by the Water Utility. No connections shall be made or allowed to exist between the public water system and any external water source, whether a private water system, well, storm runoff, recycling system, tank, vehicle or other source or method.
   (F)   Lot design.
      (1)   Minimum lot width and frontage, and setback lines.
         (a)   A subdivision may establish setback lines that are greater than the minimum requirements of the Zoning Code or other city requirements for any or all lots, by so drawing or designating such setback lines on the plat, and such setback lines shall thereafter be the minimum setback requirements for said lots. However, be it further provided that such increased setbacks shall not be used to circumvent minimum lot width or frontage requirements, which shall continue to be measured respectively at the minimum front setback line as specified by the Zoning Code and at the street right-of-way line.
         (b)   Setback lines shall parallel the street right-of-way. Minimum lot widths and frontage shall be measured parallel or radial to the right-of-way line respectively for straight or curved segments.
         (c)   All lots shall front onto a street and obtain vehicular access from a street. Lots that front onto a public street shall have a minimum of 45 feet of frontage, or 75% of the minimum lot width required by the Zoning Code if the minimum lot width requirement is less than 70 feet for the zoning district in which the lot is located, except for lots that front on cul-de-sac turnarounds. The frontage of lots on cul-de-sac turnarounds shall be not less than 65% of the minimum lot width required by the Zoning Code for the zoning district. In all cases, minimum frontages shall be as measured within a single segment of right-of-way, in the case of intermittent or multiple frontages.
      (2)   Lots with frontage on arterial or collector streets.
         (a)   The minimum setback along an arterial street shall be 50 feet or the minimum required by the Zoning Code, whichever is more. The minimum setback along a collector street shall be 35 feet or the minimum required by the Zoning Code, whichever is more. Said minimum setbacks shall apply regardless of whether the adjoining yard is a front, side or rear yard.
         (b)   Corner lots that have a side yard on an arterial street shall be a minimum of 40 feet wider than the minimum lot width required by the zoning district. In all other cases, corner lots shall be a minimum of 20 feet wider than the minimum lot width required by the zoning district.
         (c)   Lots that front on or back up to an arterial street shall have a minimum lot depth of 175 feet, and in all other cases the minimum lot depth shall be 120 feet. Lot depths shall be measured at the shallowest point of the lot, perpendicular or radial to the right-of-way line respectively for straight or curved segments.
      (3)   Buffer yards. Buffer yards and improvements thereto shall be provided by the developer along arterial streets in accordance with the minimum requirements of the Zoning Code, or such additional requirements that the City Council may be stipulate as a condition of approval of a plat. All fences, berms and buffer yard plantings and improvements shall conform to the Zoning Code.
      (4)   Grading.
         (a)   All lots in proprietor’s plats shall be graded to be entirely one foot or more above the base flood elevation as determined by the Federal Emergency Management Agency (FEMA) for a regulatory flood having a one percent or less chance of occurring in any one year, or any such higher standard that may hereafter be adopted by FEMA, and to allow basements that will be not less than one foot above the base flood elevation of the regulatory flood to be included in single-family detached residential and any and all other development that customarily is constructed with basements or other low enclosed building areas, on all lots. The developer shall cause minimum floor elevations (MFE) that are fully compliant with city and FEMA regulations to be noted on the final plat for all lots that fall all or in part within a flood hazard area as it existed prior to any improvement or development, and by restrictive covenant or other means cause all basements and all other sub-grade structures to be constructed and remain in perpetual compliance with said minimum floor elevations (MFE) , regardless of whether a letter of map revision based on fill (LOMR-F) is approved by FEMA for any or all of the lots following improvement.
         (b)   Minimum opening elevation (MOE) requirements are intended to protect property only from localized storm runoff or shallow flooding, and shall not be allowed or construed to satisfy or comply with FEMA requirements or city code requirements and intent to protect persons and property from the dangers and adverse effects of flooding, regardless of whether a LOMR-F has been obtained for a property. MOE requirements shall be construed to apply to an entire lot and all portions of every building unless an exception is expressly noted and approved with whatever conditions and limitations that are deemed appropriate for any such exception, including, but not limited to, a case where MOE protection is necessary for surface water flowage or stormwater management that is contained within a public easement on a portion of a lot, and does not affect the entire lot. Such exception may be noted on a plat and approved by the City Council, or may be administratively approved in writing by the City Engineer and Director of Community Development.
   (G)   Sidewalks and trails. Public sidewalks with a minimum width of five feet shall be constructed from portland cement concrete (“PCC”) along the frontages of all public streets and along not less than one side of all common private access drives, unless alternative routing such as a rear lot walkway or open space trail system is approved by the City Council in lieu thereof. Pedestrian and bicycle trail systems shall have a minimum width of eight feet when located within a park or open space corridor, and ten feet when located within or in proximity to a street right-of-way, and shall be constructed of PCC unless an alternative material is approved by the City Engineer. Base preparation and all other construction specifications shall be fully compliant with SUDAS standards as adopted and amended by the city.
   (H)   Miscellaneous requirements.
      (1)   Extension of improvements to boundaries. Subdivision developers shall extend all subdivision improvements to the boundaries of the subdivision at the developer’s expense, in such locations and manners as the City Engineer and City Council, Urbandale or Urbandale/Windsor Heights Sanitary Sewer District or Water Utility determine to be necessary and appropriate to serve or facilitate other development or subdivisions.
      (2)   Street names.
         (a)   Street names shall conform to the names of existing Urbandale streets that align, more or less. Numeric designations shall be used to name streets with generally north-south orientations and following the existing numbering pattern, unless an alphabetical name is already in use or block configurations prevent the use of a numbered street. Alphabetical name designations shall be used on streets with generally east-west orientations.
         (b)   If an existing street name has not been established, or an existing name is deemed to be inappropriate because of potential confusion;, undesirable slang usage or other association; or some other reason, a street name shall be assigned by the city. In no case shall new street names be selected or assigned that are closely associated with a specific subdivision, and to thereby possibly be deemed undesirable for repeated use in other subdivisions.
      (3)   Street and traffic-control signs. Street name and traffic-control signs and pavement markings shall be installed by the developer as required subdivision improvements. Street name signs shall be at all new intersections within and bordering the subdivision, and traffic control signs and pavement markings including parking prohibitions and restrictions shall be installed and provided along all streets in the subdivision, all in accordance with SUDAS and the Uniform Traffic Manual.
      (4)   Street lights. The developer shall cause plans and specifications to be prepared for street lighting on all new public streets within the subdivision, for approval by the City Engineer and MidAmerican Energy or its successor in interest. Upon approval of said plans and specifications the developer shall cause the lights to be installed in accordance with said plans and specifications, as part of the required subdivision improvements along all streets in the subdivision, all in accordance with SUDAS and the Manual on Uniform Traffic-Control Devices (MUTCD). Wooden poles and overhead wiring shall be prohibited.
      (5)   Reserve strips.
         (a)   Proprietor’s plats shall not create or perpetuate outlots that are intended to prevent adjoining properties from having access to subdivision improvements that are or will be dedicated to the city unless such outlot is expressly approved by the City Council at the time of preliminary plat.
         (b)   If such an outlot is approved, the approval shall be conditioned upon agreement by the developer to convey the outlot to the city within not more than ten years following the date of final plat approval, and that it shall thereafter become city right-of-way without any restriction of access to, over, and across such right-of-way by reason of the aging and reduced life expectancy of the dedicated subdivision improvements, and the continual investment of public funds to maintain, preserve and reconstruct such improvements. If such conditions are not acceptable to the developer, or challenged as an unconstitutional taking by the developer or a successor in interest, the Council’s approval of the plat shall be deemed null and void and the city may take action in accordance with Iowa Code § 354.20 to annul the plat.
      (6)   Disposal of waste materials. No wood, vegetation, debris, junk, rubbish, garbage or other waste materials of any kind, whether organic or inorganic, shall be left, deposited or buried on any portion of a lot or in any parcel that is to be dedicated to the city or other governmental entity, or to an owners’ association, and shall be completely removed from the subdivision prior to releasing of the subdivision plat for recording, unless an alternative to complete removal is expressly approved by the City Council.
      (7)   Public utility lines. All public utility lines and appurtenances thereto, including, but not limited to, electrical and telecommunication lines, shall be buried underground within easements provided for said public utilities in accordance with § 159.09. The developer shall be responsible for making the necessary arrangements with each of the serving utilities to comply with this requirement, including payment of any construction or installation charges or fees by any utility company.
      (8)   Bench marks. The developer shall cause all subdivision and lot corners, points of curvature, et al., to be installed in accordance with the Code of Iowa. The developer shall cause a minimum of one permanent bench mark to be set, certified, and made of record by a land surveyor who is licensed in the state as part of the subdivision improvements for a proprietor’s plat, unless the City Engineer determines that sufficient bench marks exist within the general vicinity.
   (I)   Inspections.
      (1)   All subdivision improvements shall be inspected by the Engineering Department to ensure that such Improvements are in compliance with the approved subdivision plans and specifications; Statewide Urban Design and Specifications (SUDAS) as adopted and amended by the city; and all other applicable city and state regulations. All costs for said inspections shall be paid by the developer, including, but not limited to, the cost of employee salaries and benefits, administrative costs and laboratory testing fees or charges.
      (2)   Laboratory and field tests shall be taken in accordance with SUDAS as adopted and modified by the city, and in addition thereto whenever deemed necessary by the City Engineer to determine compliance with city specifications and with professional standards.
      (3)   An improvement shall not be accepted or approved for public use if it has not been properly inspected; has not passed all inspections and testing; or is otherwise determined by the City Engineer to potentially not be fully compliant with the approved subdivisions improvement plans and specifications, SUDAS as amended and adopted by the city, this Code, or other required standards and specifications. It shall be the developer’s duty to document and prove, by whatever means may be necessary that the improvement in question does in fact fully comply with this Code and all other applicable codes and regulations.