Subdivision Design and Public Realm

Purpose. This chapter sets the design standards for the subdivision of land within the City — the layout of blocks, lots, and the public realm, and the provision of pedestrian, bicycle, and open-space infrastructure that accompanies subdivision development. The chapter implements Title 76, chapter 25, MCA, Part 4, in particular the substantial-compliance review standard at 76-25-304, by stating in advance the design requirements a subdivision must meet to comply with this title.

Applicability. This chapter applies to every division of land within the City that is subject to subdivision review under Chapter 3, including major subdivisions, administrative minor subdivisions, and amendments to recorded plats. It does not apply to divisions of land that are exempt from subdivision review under 76-25-401(2) and 76-3-201, MCA.

Relationship to other chapters. Chapter 3 carries the procedures and review-type assignments for subdivision applications, including the dual appeal-track structure for administrative minor subdivisions under 76-3-609. Chapter 6 carries the public-improvement installation, dedication, and financial-security mechanics. The City of Helena Engineering and Design Standards carry the construction specifications for the public improvements this chapter calls for.

Conflicts. Where a standard in this chapter conflicts with a standard in the Engineering Standards, the standard that is more protective of public health and safety controls; where the Engineering Standards are silent and this chapter speaks, this chapter controls; where this chapter is silent and the Engineering Standards speak, the Engineering Standards control.

Conformance with adopted plans. The design of a subdivision must conform to the adopted Land Use Plan, the adopted Long Range Transportation Plan, the adopted Downtown Helena Multimodal and Infrastructure Plan where applicable, and any adopted neighborhood plan applicable to the subdivision site under 76-25-214. Conformance is reviewed as substantial compliance under 76-25-304(2)(c).

Conformance with zoning. The design of a subdivision must conform to the zoning district applicable to the subdivision site, including the form, dimensional, and site design standards of Chapter 4, the use standards of Chapter 2, and the A-grid and B-grid layer of the Official Zoning Map. A subdivision is not a vehicle for varying or avoiding the zoning standards otherwise applicable to the site.

Conformance with the Engineering Standards. The design of a subdivision must conform to the Engineering Standards, which govern the construction and physical specification of streets, utilities, stormwater facilities, and other public improvements within and adjacent to the subdivision.

Sequencing. The standards in this chapter establish the design framework the subdivision must meet at preliminary plat. The Engineering Standards, applied at the construction-plan stage, establish the construction framework the subdivision must meet before final plat. The two reviews are sequenced rather than parallel.

Block configuration. Blocks must be designed for the safe and convenient movement of vehicles, pedestrians, and bicycles, and to support the orderly development of lots. Block length, width, and shape must be appropriate to the use and density of the proposed lots, the site's topography, and the surrounding street network.

Block length — standards by district family.

Pedestrian throughways. Where a block exceeds 500 feet, a mid-block pedestrian throughway is required, connecting the two longer block faces at a point approximately equidistant from the cross streets. The throughway must be at least 10 feet wide, designed as a public access easement or right-of-way, and constructed to the pedestrian-facility specifications in the Engineering Standards.

Connectivity. The subdivision's street network must connect to existing and planned streets adjoining the site at intervals that support the network's role in the surrounding area. Cul-de-sacs and other dead-end streets are permitted only where topography, environmental constraints, or existing development patterns make through-street connections infeasible; in those cases, a pedestrian or bicycle connection is provided in lieu of the through-street where reasonable.

Lot dimensions. Lot area, width, and depth must conform to the dimensional standards of Chapter 4 for the zoning district in which the lot is located. Where Chapter 4 sets no minimum, this chapter sets no minimum.

Lot orientation. Every lot must front on a public street or on an approved private street that meets the public-street design standards. Flag lots are permitted only where topography or existing parcel configuration makes a conventional frontage configuration infeasible, and only with a written finding by the Planning Administrator that the flag-lot design meets the access, utility, and emergency-services requirements of the Engineering Standards.

Side lot lines. Side lot lines must be drawn substantially perpendicular to the street the lot fronts, except where topography or block configuration justifies an alternative orientation.

Double-frontage lots. A lot that fronts on two parallel public streets (a double-frontage lot) is permitted only where topography or existing access constraints make a single-frontage configuration infeasible. Where a double-frontage lot is permitted, the lot must be designed with a clear primary frontage, and the lot line abutting the secondary street is treated as a B-frontage under Chapter 4.

Lots abutting arterials. A lot that abuts a principal or minor arterial street, as classified in the adopted Long Range Transportation Plan, may not take primary access from the arterial unless no other access is feasible. Where arterial access is unavoidable, the access is reviewed under the Engineering Standards' driveway-access provisions.

Street classifications. Streets within the subdivision are classified according to the Long Range Transportation Plan's functional classification system — principal arterial, minor arterial, major collector, minor collector, and local street. The classification determines the design standard the street must meet, as specified in the Engineering Standards.

New street alignment. The alignment of new streets must continue the alignment of existing adjacent streets where reasonable, support the block-design standards in Section 11-5-3, and minimize disturbance to topography and natural features.

Right-of-way widths. Minimum right-of-way widths for each functional classification are specified in the Engineering Standards. This chapter does not restate them.

Sidewalks. Sidewalks are required on both sides of every street within the subdivision, with widths as specified in the Engineering Standards. Sidewalks must connect to the existing sidewalk network at the subdivision's boundaries. Where a sidewalk would terminate at an undeveloped property line, the sidewalk is constructed to the property line so that the next development can connect to it.

Bicycle facilities. Where the adopted Long Range Transportation Plan or the adopted Downtown Helena Multimodal and Infrastructure Plan designates a corridor for bicycle infrastructure, the subdivision must provide the bicycle facility designated for that corridor, constructed to the Engineering Standards' specifications.

Boulevard landscaping. Boulevard areas between the curb and the sidewalk must be landscaped — typically with turf and street trees — in conformance with the Engineering Standards and the Landscaping chapter of this UDO.

Street naming. New streets must be named in conformance with the City's street-naming policy. A new street name may not duplicate an existing street name in the City or in Lewis and Clark County. The name must be approved by the Planning Administrator at preliminary plat.

Parkland dedication. A subdivision creating six or more residential lots must dedicate parkland or provide an equivalent contribution in cash or land, in accordance with 76-3-621, MCA. The dedication is calculated as eleven percent of the area of the land proposed to be subdivided into parcels of one-half acre or smaller, or as the equivalent of 0.03 acres per dwelling unit for parcels larger than one-half acre, whichever is greater, with the cap and exemptions in 76-3-621 applied.

Parkland location and configuration. Dedicated parkland must be configured as a usable park or open-space site — not as a residual remainder, a steep slope, a stormwater facility, or a stripe of land along a property line. The Planning Administrator may accept parkland that includes a stormwater facility only where the facility is designed to function as a usable open-space amenity. The Parks Division reviews parkland dedications under the Engineering Standards' parks-and-trails provisions.

Cash-in-lieu. Cash-in-lieu of parkland dedication is permitted under 76-3-621(2) where the City accepts it, and is calculated as the value of the equivalent parkland under that statute. Cash-in-lieu is deposited in the City's parkland fund and used for parkland acquisition, development, or improvement in accordance with the City's parkland policy.

Trails and pedestrian connections. Where the adopted Long Range Transportation Plan, the adopted Downtown Helena Multimodal and Infrastructure Plan, or an adopted neighborhood plan designates a trail or pedestrian connection across or adjacent to the subdivision site, the subdivision must provide the designated connection, dedicated as a public-access easement or as a public right-of-way at the City's option.

Stormwater facilities as public realm. Where a subdivision's stormwater facilities are visible from a public street or sidewalk, the facilities must be designed as integrated landscape features rather than as bare detention basins. The Engineering Standards' stormwater specifications control the facility's hydraulic performance; this chapter controls the facility's visual integration into the public realm.

Utility easements. Easements for water, wastewater, stormwater, gas, electric, and communications utilities must be provided along the boundaries of lots and along rear lot lines in conformance with the Engineering Standards.

Drainage easements. Drainage easements must be provided where stormwater runoff crosses property lines or where stormwater facilities are located on private property.

Access easements. Cross-access easements between adjacent lots may be required by the Planning Administrator where the access supports the connectivity standard in Section 11-5-3(D), serves shared parking or shared driveway arrangements, or implements the arterial-access management standard in Section 11-5-4(E).

Conservation easements. Conservation easements are permitted to protect environmentally sensitive areas, hillsides, riparian corridors, or other natural features, and may be required as a condition of subdivision approval where the subdivision proposes to develop adjacent to a natural feature the City has identified as warranting protection.

Hillside subdivisions. A subdivision on a site with slopes greater than fifteen percent must be designed to minimize disturbance to natural topography, vegetation, and drainage patterns. The subdivision design must show pre- and post-development topography; the cuts, fills, and retaining structures the design requires; and the erosion and sediment controls that will be installed during and after construction.

Wildland-urban interface. Subdivisions within the wildland-urban interface, as mapped under the Overlay chapter (Chapter 16), must comply with the WUI standards in that chapter in addition to the requirements of this chapter.

Floodplains. Subdivisions within a mapped floodplain must comply with the City's floodplain regulations and with 76-25-303 limitations on zoning authority over floodplain development.

Steep slopes as parkland. A lot or portion of a lot with slopes greater than thirty percent is not counted toward the parkland dedication area calculation under Section 11-5-6(A) unless the steep-slope area is configured and improved as a usable open-space amenity.

Required submittals. A subdivision application must include the design submittals specified in the Engineering Standards plus the following design submittals required for the Chapter 3 substantial-compliance review under 76-25-304

Form. Submittals must be in the form specified in the Engineering Standards or, where the Engineering Standards do not address the submittal form, in the form specified by the Planning Administrator.

Application materials. The Community Development Department maintains the subdivision application materials, which include the submittal checklist, the application form, the fee schedule, and any guidance documents the Planning Administrator publishes to facilitate compliance with this chapter.

Variance authority. A variance from a standard in this chapter may be granted by the Planning Administrator under 76-25-502, MCA, in accordance with the variance procedure in Chapter 3 and the variance criteria in this section. A variance from a standard in the Engineering Standards is reviewed by the City Engineer under those standards' own variance procedure and is not within the scope of this section.

Criteria. A variance from a standard in this chapter may be granted only on findings that

Conditions. The Planning Administrator may attach conditions to a variance that are necessary to satisfy the criteria in subsection B.

Appeal. The decision on a variance is final at the Planning Administrator level and is subject to appeal under 76-25-503, MCA, as specified in Chapter 3.