Town of Horizon City, TX SECTION 5 SUBDIVISION PLAT DESIGN STANDARDS [1]

[1] Editor’s note–Section 5 was substantially revised by Ordinance 0035-013. In addition to other changes, the ordinance changed the subject matter of sections 5.2, 5.3, 5.8, 5.9 and 5.16. Prior to such amendment, these sections derived from Ordinance 0035 and Ordinance 0035-009.

§ 5.1 GENERAL REQUIREMENTS.

No development shall be approved unless the subdivider provides for the construction of such streets and sidewalks as are necessary to serve the proposed development in accordance with the requirements and design standards of this Article [this ordinance].

The layout of streets shall provide for integrating new development with existing and future development in a manner that provides for traffic safety, public convenience, emergency access, and traffic patterns consistent with the land uses and intensities proposed by city’s Master Plan.

(Ordinance 0035 adopted 1/11/94; Ordinance 0035-013 adopted 7/20/04)

§ 5.2 CONFORMANCE TO MAJOR THOROUGHFARE PLAN REQUIRED.

5.2.1 No development shall be approved that is in conflict with, or would otherwise impede the implementation of, the city’s Major Thoroughfare Plan.

5.2.2 When a property proposed for development includes all or any portion of a major thoroughfare, as designated by the city’s Major Thoroughfare Plan, the developer shall incorporate said thoroughfare in the subdivision layout. The developer shall consult with the Planning Director prior to submitting a preliminary plat regarding the required width of the thoroughfare.

5.2.3 Because development of property has the potential of increasing vehicular traffic on streets adjacent to and beyond the boundaries of the development, a rational nexus shall be presumed to exist between the development of property and the need for thoroughfare improvements. In no instance shall a developer be exempted from dedicating the necessary right-of-way for a planned thoroughfare that would cross all or any portion of his, her or their development. The City Council may, however, exempt a developer from having to fully improve a thoroughfare provided the developer submits a traffic impact study that demonstrates that such full improvements are neither necessitated by, nor attributable to, the new development.

5.2.4 No property owner shall be relieved of the responsibility of dedicating and improving his, her, or their portion of a major thoroughfare by virtue of having subdivided all or any portion of a parcel by metes and bounds or any other means other than a publicly approved and filed subdivision plat.

(Ordinance 0035-013 adopted 7/20/04)

§ 5.3 COORDINATION WITH SURROUNDING STREETS.

5.3.1 The street system for each development shall be coordinated with existing, proposed and anticipated streets within and outside the development, and streets shall be extended outside the development when necessary for adequate access, safe traffic circulation, or for other reasonable traffic considerations.

5.3.2 Streets shall be aligned with existing or proposed streets of adjoining properties, except where the city’s Master Plan, topographic conditions, requirements of traffic circulation, or other planning considerations make it desirable to depart from the alignment.

5.3.3 Stub-end streets, extended to the property line of a development, shall be provided whenever a development abuts unplatted, undeveloped land so as to avoid land-locking property and to provide for the needs of future development. Such stub-end streets shall generally be spaced no further than one thousand three hundred (1,300) feet (~396 m) apart so as to avoid excessive block lengths.

5.3.4 The extension of residential or collector streets may be denied if it is determined that the extension would provide for an unacceptable use of the street for substantial through traffic.

(Ordinance 0035-013 adopted 7/20/04)

§ 5.4 LOT FRONTAGE AND ADEQUATE ACCESS.

All developments shall provide a network of streets, on-site and off-site, as necessary to ensure safe and adequate access to the development and to each lot therein, and each lot in a subdivision shall abut on a dedicated public or private street meeting or exceeding the requirements of these specifications.

In determining the access requirements for a development, the following shall be considered:

5.4.1 Access for police, fire and other emergency vehicles, in terms of both street cross-section and time-of-response;

5.4.2 The condition and trafficability of existing streets outside of the development but necessary for gaining access to the development;

5.4.3 Congestion that may be created at proposed or existing intersections as a result of the development;

5.4.4 Provision of more than a single means-of-access to developments likely to generate more than five thousand (5,000) vehicle trips per day; and,

5.4.5 Any other condition, existing or proposed, that may affect public safety.

(Ordinance 0035 adopted 1/11/94; Ordinance 0035-013 adopted 7/20/04)

§ 5.5 STREET RIGHT-OF-WAY WIDTHS.

The minimum street right-of-way widths in subdivisions shall not be less than fifty-two feet (52') for local streets.

5.5.1 The minimum street right-of-way widths in all subdivisions shall not be less than fifty-two feet (52') for minor residential streets, except cul-de-sacs of seven hundred fifty feet (750') in length or less, may be fifty feet (50'); sixty-four feet (64') for neighborhood collector streets; seventy-six feet (76') for thoroughfares and industrial streets; eighty-four feet (84') for arterials; and one hundred and twenty feet (120') for State designated roadways.

5.5.2 

Street Widths.

When the land proposed to be subdivided is partially or totally bounded on one or more sides by a street, way or thoroughfare having a width less than that specified in street right-of-way (ROW) widths, such land shall be laid out so as to provide street widths specified herein. No lots shall front on an existing substandard ROW width unless additional ROW is dedicated to upgrade the ROW width standards as specified herein.

(Ordinance 0035 adopted 1/11/94; Ordinance 0035-009 adopted 9/10/02)

§ 5.6 IMPROVEMENT TO EXISTING OFF-SITE STREETS.

5.6.1 Wherever a development is to utilize existing road frontage, such road frontage shall be improved sufficient to provide for the safe movement of the amount and type of traffic generated by the development. Such off-site street improvements or repairs need not meet the specifications for new streets, but shall include such patching, reconstruction or the providing of asphalt overlays as are determined necessary by the City Engineer.

5.6.2 A developer shall not be required to make off-site street improvements beyond the nearest intersecting arterial or collector streets.

(Ordinance 0035-013 adopted 7/20/04)

§ 5.7 EASEMENTS - GENERALLY.

City Subdivisions: Easements for utilities and/or roadway drainage may be required across parts of lots or along lot lines as required by the City Engineer for normal roadway drainage relief. A spacing, not to exceed four hundred ft. (400') along the roadway, shall be used for drainage easements unless analysis of runoff shows greater spacing is required.

5.7.1 

Drainageway Easements:

Easements shall be retained along drainage ways which cross proposed roads, which carry drainage away from roads, or which convey main drainage from and through the lots or tracts. Easements shall be a minimum of fifteen feet (15') wide. Easement alignment shall follow the appropriate line of the channel on maximum fifty feet (50') chords, and wherever possible, shall be located along lot lines. A suitable note on the plat must restrict all properties within the subdivision insuring that drainage easements within the plat boundaries shall be kept clear of fences, building, planting and other obstructions to the operations and maintenance of the drainage facility. The abutting property shall not be permitted to drain directly into this easement except by means of a drainage structure approved by the City Engineer.

5.7.2 

Privately Owned Easements, Fee Strips:

All easements or fee strips created prior to the subdivision of any tract of land must be shown on the subdivision plat with appropriate notations indicating the name of the holder of such easement or fee strip, the purpose of the easement and the facilities contained therein, the dimensions of the easement or fee strip tied to all adjacent lot lines, street right-of-way and plat boundary lines and the recording reference of the instruments creating and establishing said easement or fee strip. In those instances where easements have not been defined by accurate survey dimensions, such as “over and across” type easements, the easement to accurately define the limits and location of his easement through the property within the plat boundaries.

If the holder of such undefined easement does not define the easement involved and indicates his refusal to define such easement to the City Engineer, the subdivision plat must provide accurate information as to the centerline location of all existing pipelines or other utility facilities placed in conformance with the easement owners’ rights.

A letter, statement, or other instrument from the owner of any privately owned easement, or fee strip within the plat boundaries must be provided where such easements or fee strips are proposed to be crossed by streets (either public or private) or public utility or drainage easements, stating that the owner of such easement or fee strip approves such crossing of his/her private easements or fee strips for the purposes intended and depicted upon the plat.

Where an instrument of record is submitted in lieu of a letter or statement from the owner of any such private easement of [or] fee strip, the City Engineer shall then refer such instrument to the City Attorney for a determination as to whether the condition[s] in such instrument are sufficient to adequately provide or accommodate the crossings of such private easement or fee strip by the proposed streets (either public or private) or public utility or drainage easements depicted on the plat.

5.7.3 

ETJ Subdivisions:

Easements shall be as established under the appropriate municipality’s subdivision requirements for ETJ subdivisions.

(Ordinance 0035 adopted 1/11/94)

§ 5.8 CONSTRUCTION STANDARDS.

5.8.1 All required street improvements shall comply with the Subdivision Design Improvement Standards, which are appended to this Article [this ordinance].

5.8.2 Street pavement sections shall be designed based on the type and volume of expected traffic at full development.

5.8.3 All required street improvements shall be constructed in accordance with applicable elements of the Standard Specifications for Construction and Maintenance of Highways, Streets and Bridges, 2004 edition, as published by the Texas Department of Transportation.

(Ordinance 0035-013 adopted 7/20/04)

§ 5.9 ROAD MANAGEMENT DATA.

The developer shall supply the City Engineer a 3-1/2" data diskette with pertinent information necessary for the addition of streets within the proposed subdivision for inclusion into the City Pavement Management System. The City Engineer shall supply the developer the format for preparation of the data diskette.

If the developer cannot provide the data diskette, then the City Engineer will acquire the pertinent information from the developer on a prepared form and assess a service charge to the developer.

(Ordinance 0035-013 adopted 7/20/04)

§ 5.10 TOPOGRAPHY AND ARRANGEMENT.

5.10.1 Roads shall be related appropriately to the topography. Local roads shall be curved wherever possible to avoid conformity of lot appearance. All streets shall be arranged so as to obtain as many as possible of the building sites at, or above the grades of the streets. Grades of streets shall conform as closely as possible to the original topography. A combination of steep grades and curves shall be avoided. Specific standards are contained in the design standards of these Regulations.

5.10.2 All streets shall be properly integrated with the existing and proposed system of thoroughfares and dedicated rights-of-way.

5.10.3 Minor or local streets shall be laid out to conform as much as possible to the topography, to discourage use by through traffic, to permit efficient drainage and utility systems, and to require the minimum number of streets necessary to provide convenient and safe access to property.

5.10.4 Proposed streets shall be extended to the boundary lines of the tract to be subdivided, unless prevented by topography or other physical conditions, or unless in the opinion of the City Engineer such extension is not necessary or desirable for the coordination of the subdivision with the existing layout or for the most advantageous future development of adjacent tracts.

(Ordinance 0035 adopted 1/11/94)

§ 5.11 BLOCKS.

5.11.1 Blocks shall have sufficient width to provide for two (2) tiers of lots of appropriate depths. Exceptions to this prescribed block width shall be permitted in blocks adjacent to major streets, railroads or waterways.

5.11.2 The lengths, widths, and shapes of blocks shall be such as are appropriate for the locality, and the type of development contemplated, but block lengths in residential areas shall not exceed one thousand three hundred (1,300) feet nor be less than four hundred (400) feet in length.

(Ordinance 0035 adopted 1/11/94)

§ 5.12 ACCESS TO PRIMARY ARTERIALS.

Where a subdivision borders on or contains an existing or proposed primary arterial, access for residential lots from such streets shall be limited by one of the following means:

5.12.1 The subdivision of lots so as to back onto the primary arterial and front onto a parallel local street; no access shall be provided from the primary arterial.

5.12.2 A series of cul-de-sacs, U-shaped streets, or short loops entered from a [and] designed generally at right angles to such a parallel street, with the rear lines of their terminal lots backing onto the major arterial.

(Ordinance 0035 adopted 1/11/94)

§ 5.13 RESERVE STRIPS.

The creation of reserve strips shall not be permitted adjacent to proposed streets in such a manner as to deny access from adjacent property to such street.

(Ordinance 0035 adopted 1/11/94)

§ 5.14 CONSTRUCTION OF ROADS AND STUB-END ROADS.

5.14.1 

Construction of Roads.

The arrangement of streets shall provide for the continuation of principal streets between adjacent properties when such continuation is necessary for convenient movement of traffic, effective fire protection or for efficient provision of utilities. If the adjacent property is undeveloped and the street must be a temporary stub-end street, the right-of-way shall be extended to the property line. A temporary T- or temporary L-shaped turnabout shall be provided on all temporary stub-end streets, with the notation on subdivision plat, if applicable, that the land outside the normal street right-of-way shall revert to abutters whenever the street is continued. The City Engineer may limit the length of temporary stub-end streets in accordance with the City Design Standards of these Regulations.

5.14.2 

Stub-End Streets.

Where a road does not extend beyond the boundary of the subdivision and its continuation is not required by the City Engineer for access to adjoining property, its terminus shall normally not be nearer to such boundary than fifty (50) feet. However, the City Engineer may require the reservation of an appropriate easement to accommodate drainage facilities for utilities. A cul-de-sac turnaround shall be provided at the end of a [stub-end street and] permanent stub-end streets shall, in general, be limited in length in accordance with the City Design Standards of these Regulations.

(Ordinance 0035 adopted 1/11/94)

§ 5.15 DESIGN STANDARDS.

5.15.1 

General.

In order to provide for roads of suitable location, width, and improvement to accommodate prospective traffic, and afford satisfactory access to police, firefighting, sanitation, and road maintenance equipment, and to coordinate roads so as to compose a convenient system and avoid undue hardships to adjoining properties, the design standards for roads as enumerated below and as depicted in the Subdivision Design Improvement Standards that are appended to this Ordinance are hereby required.

5.15.2 

Intersections:

5.15.2.1 Streets shall be laid out so as to intersect as nearly as possible at a ninety-degree angle. Curvilinear streets shall generally be designed with a tangent section not less than 100 feet (~30 m) in length at the approach [to] an intersection. Not more than two streets shall intersect at any one point.

5.15.2.2 Proposed intersections along one side of a street shall coincide with existing or proposed intersections on the opposite side of the street. To the extent practicable, streets of new developments shall align with existing or proposed streets within surrounding developments except where, in the opinion of the City Engineer, topography, requirements of traffic circulation or other considerations make it desirable to depart from such alignment. Where an offset (jog) in street alignment is unavoidable, the minimum offset in street centerlines shall be 150 feet (~46 m).

5.15.2.3 Streets shall not intersect at a point where horizontal or vertical curves or other obstructions to visibility would restrict sight distance to less than that of the stopping sight distances for the class of the respective intersecting streets.

5.15.2.4 Street intersections shall be designed with a relatively flat grade whenever possible. In hilly areas, a street approaching an intersection shall not have a grade in excess of two percent (2%) for a distance of sixty (60) feet (~18 m), as measured from the nearest projected right-of-way line of the intersecting street.

5.15.2.5 Minimum paving radius at the intersection of two (2) residential streets shall be at least twenty (20) feet; and minimum paving radius at an intersection involving a collector street shall be at least twenty-five (25) feet.

5.15.2.6 The cross-slopes on all streets, including intersections, shall be three percent (3%) or less.

5.15.3 

Medians:

5.15.3.1 When any development is required to provide more than one-half of any arterial street, a median shall be provided in accordance with the Subdivision Design Improvement Standards that are appended to this Chapter [this ordinance].

5.15.3.2 Developments may provide medians as part of Residential Collector Streets, as provided by the Subdivision Design Improvement Standards, but such median surfaces must be landscaped with drought-tolerant, low-maintenance plant materials. The developer shall submit plans for such median landscaping to the Director of Public Works. Approval of such median landscaping by the Director of Public Works shall be required prior to the recording of the subdivision plat.

5.15.4 

Cul-de-sacs and Dead-end Streets:

5.15.4.1 Cul-de-sacs or loop streets may be used to discourage through traffic on residential or local streets.

5.15.4.2 The length of the street that terminates in a cul-de-sac shall not be more than seven hundred (750) feet (~230 m), measured from the center point of the cul-de-sac to the centerline of the nearest intersecting street.

5.15.4.3 The right-of-way of a cul-de-sac shall have a minimum radius of fifty (50) feet (~15 m). The City Engineer may require a larger radius if a cul-de-sac is to serve nonresidential development.

5.15.4.4 In circumstances were [where] a street provides the sole means of access to one or more building lots, and where such street terminates at a development boundary from which it is later to be extended by a subsequent development, the developer shall provide a temporary turnaround, and said temporary turnaround shall be contained within a easement so designated on the subdivision plat.

5.15.4.5 All permanent cul-de-sacs shall be built in accordance with design standards for streets and shall be provided with curbs and gutters. Temporary cul-de-sacs for dead-end streets that are proposed to be extended shall be designed and built in accordance with the Subdivision Design Improvement Standards that are appended to this Chapter.

5.15.4.6 A stub-end street or other dead-end street that does not terminate in a cul-de-sac turnaround shall not be used to give access to an individual lot development unless the requirement to develop a cul-de-sac turnaround is specifically waived by the City Council based on circumstances unique to the property.[1]

[1] Editor’s note—Original has this as Subsection 5.15.4.5.

5.15.5 

Alleys:

5.15.5.1 Alleys may be allowed in or required for developments in nonresidential zoning districts where such alleys are deemed necessary to provide access for service vehicles, off-street loading or unloading, access for emergency vehicles or similar reasons consistent with the intent of this Article.

5.15.5.2 Alleys may be allowed in residential developments zoned Planned Unit Development when the development employs alleys for accessing residential off-street parking spaces in lieu of conventional street access.

5.15.5.3 All alleys shall have at least two direct access points to local public streets; dead-end alleys will not be permitted.

5.15.5.4 Alleys shall not have direct access to arterial streets, nor shall alleys be allowed to connect to collector streets unless the City Engineer determines that there is no other reasonable means of access and such connection will not create a traffic hazard.

5.15.5.5 Alleys shall not be dedicated to the public except where such dedication is determined to serve the public interest. Alleys shall, however, be available for emergency services and for vehicles and staff of the city’s Public Works Department.

5.15.5.6 Alleys not dedicated to the public shall be subject to the private road requirements of Section 5.15.6.

5.15.6 

Private Roads:

5.15.6.1 For the purpose of this section, a “private road” shall mean any open way used for vehicular traffic, not dedicated to public use and not part of a parking lot, designed and used to provide vehicular access to a development or lot. Private roads shall generally be restricted to developments with controlled access, said access control being by means of a privately constructed entrance features and privately operated security services. Private roads shall, however, be available for emergency services and for vehicles and staff of the city’s Public Works Department.

5.15.6.2 A development may be approved with one or more private roads when:

1. Such private roads will have direct access onto one or more dedicated public streets;

2. Such private roads are not necessary or planned to serve or provide for traffic or drainage outside the development;

3. Such private roads are so routed or designed so as to discourage through traffic; and

4. Such private roads will provide for adequate access, the safe movement of traffic, drainage and generally serves as an adequate alternative to a public street.

5.15.6.3 When the private road will serve more than one lot, the developer shall submit to the City Council for approval a written and binding declaration, to be recorded concurrently with the filing of the subdivision plat, establishing an owners’ association or similar legal entity that will have:

1. The legal authority to maintain and exercise control over the road; and,

2. The power to compel contributions from owners within the development to cover their proportionate shares of the cost associated with maintenance of the road.

5.15.6.4 Private roads shall be designed and built in conformance with the Subdivision Design Improvement Standards, as referenced in Section 5.8, except that the City Engineer may approve alternative paving surfaces that provide equally well for the traffic-carrying function and durability of said roads.

5.15.6.5 Parking areas or spaces may be developed as an integral part of a private road provided that the City Engineer determines that such parking areas or spaces will not create a traffic hazard.

(Ordinance 0035 adopted 1/11/94; Ordinance 0035-013 adopted 7/20/04)

§ 5.16 PERIMETER STREETS.

5.16.1 

New Perimeter Streets.

Street systems shall be laid out so as to avoid creating partial streets that have less than the full required right-of-way and pavement width for the required class of street. However, if an arterial street is proposed by the city’s Major Thoroughfare Plan on the boundary of the development, or in close proximity to the development, or if the development creates the need for a new perimeter street, the development shall provide that portion of the perimeter street for which it reasonably creates the need, but in no case shall that portion of the street provided be less than a pavement width of thirty-three (33) feet (~10 m). All perimeter streets shall be provided with curb and gutter along the side abutting the development. If the perimeter street is ultimately proposed to serve as a divided arterial street and the development is required to install half of the arterial street, then curb and gutter shall be provided on both sides of the perimeter street so as to provide the curb for the future median of the arterial street.

5.16.2 

Existing Perimeter Streets

5.16.2.1 Any development abutting an unimproved or partially improved perimeter street shall dedicate such additional right-of-way and improve or reconstruct the street as may be necessary to complete the perimeter street to the classification required. For the purpose of this subsection, an “unimproved perimeter street” shall mean a perimeter street that does not substantially comply with the street design specifications or requirements of this Ordinance, generally given evidence by the absence of paving or curb and gutter.

5.16.2.2 Where a development would be required by this Ordinance to improve an existing unimproved perimeter street that is designated in the city’s Major Thoroughfare Plan as an arterial street to less that its full width [sic], the developer may elect in lieu of making the required perimeter street improvements, to pay to the city prior to beginning construction the total construction cost, excluding engineering and design cost, of the required street improvements. The amount to be paid shall be determined by the City Engineer, based on the actual cost of providing for the improvements, as shown in the most recent public bids for the same or similar type street improvements. If the money paid to the city is not used for the required improvements within five (5) years of payment, the funds shall be returned to the person or entity making the payment.

5.16.3 Exception to Perimeter Street Requirement. The provisions of this section requiring the improvement of existing unimproved perimeter streets to the city’s specifications for new streets shall not apply:

*	To state or federal highways
*	To roadways that are to be constructed or reconstructed as part of an approved and funded Capital Improvement project that has been awarded for construction.

(Ordinance 0035 adopted 1/11/94; Ordinance 0035-013 adopted 7/20/04; Ordinance 0035-19 adopted 12/13/16)

§ 5.17 DRAINAGE AND STORM SEWERS.

5.17.1 No subdivision shall be approved which does not make adequate provision for storm or floodwater runoff channels or basins. The stormwater drainage system shall be separate and independent of any sanitary sewer system. Storm sewers, where required, shall be designed by such methods as are approved by the City Engineer. Inlets shall be provided so that surface water is not carried across or around any intersection, nor for a distance of more than six hundred (600) feet in the gutter. When calculations indicate that curb capacities are exceeded at a point, no further allowance shall be made for flow beyond that point, and basins shall be used [to] intercept flow at that point.

5.17.2 

Nature of Stormwater Facilities

5.17.2.1 

Location.

The subdivider shall be required by the City Engineer to carry away by pipe or open ditch any spring or surface water that may exist either previously to, or as a result of the subdivision. Such drainage facilities shall be located in the road right-of-way where feasible, or in perpetual unobstructed easements of appropriate width, and shall be constructed in accordance with the City Design Standards. See Appendix for specific standards.

5.17.2.2 

Accessibility to Public Storm Sewers.

Where a public storm sewer is accessible, the subdivider shall install storm sewer facilities. If no outlets are located within a reasonable distance, adequate provision shall be made for the disposal of stormwaters, subject to the specifications of the City Engineer. However, in subdivisions containing lots less than 10,000 square feet in area, served by central sewage facilities and served by an approved public water system, storm sewer systems shall be constructed throughout the subdivision.

5.17.2.3 

Accommodation of Upstream Drainage Areas.

A culvert or other drainage facility shall in each case be large enough to accommodate potential pass-through runoff from its entire upstream area, whether inside or outside the subdivision. The City Engineer shall determine the necessary size of the facility, based on the provisions of the City Design Standards and specifications assuming conditions of maximum potential watershed development.

5.17.2.4 

Effect on Downstream Drainage Areas.

The City Engineer shall also study the effect of each subdivision on existing downstream drainage facilities outside the area of the subdivision. City drainage studies together with such other studies as shall be appropriate, shall serve as a guide to needed improvements. Where it is anticipated that the additional runoff incident to the development of the subdivision will overload an existing downstream drainage facility, the City Council shall withhold approval of the subdivision until provision has been made for the improvement of said potential condition. No subdivision shall be approved unless adequate drainage will be provided to an adequate drainage watercourse or facility.

5.17.2.5 

Areas of Poor Drainage.

The subdivision of an area which is subject to flooding may be approved by the City Council provided that the subdivider fills the affected area of said subdivision to an elevation sufficient to place the elevation of streets and finish floor elevation of structures at a minimum of twelve (12) inches above the elevation of the maximum probable flood. Any modifications must be in accord with any proposed sewage disposal plan for the area.

5.17.3 

Dedication of Drainage Easements

5.17.3.1 

General Requirements.

Where a subdivision is traversed by a watercourse, drainageway, channel, or stream, there shall be provided a stormwater easement or drainage right-of-way conforming substantially to the lines of such watercourse, and of such width and construction as will be adequate for the purpose. Whenever possible, it is desirable that the drainage be maintained by an open channel and adequate width for maximum potential area of flow.

5.17.3.2 Drainage Easements

5.17.3.2.1 Where topography or other conditions are such as to make impractical the inclusion of drainage facilities within road rights-of-way, perpetual unobstructed easements at least fifteen (15) feet in width for such drainage facilities shall be provided across property outside the road lines and with satisfactory access to a road. Drainage easements shall be carried from the road to a natural watercourse or to other drainage facilities.

5.17.3.2.2 When the proposed subdivision drainage system will carry water across private land outside the subdivision, appropriate drainage rights must be secured.

5.17.3.2.3 The subdivider shall dedicate, either in fee or by drainage easement, land on both sides of existing watercourses to a distance to be determined by the City Road Engineer.

5.17.3.2.4 Low-lying lands along watercourses subject to flooding or overflowing during storm periods, whether or not included in areas for dedication, shall be preserved and retained in their natural state as drainage ways. Such land or lands subject to periodic flooding shall not be included in determining the area requirement for any lot.

5.17.4 

Drainage Ponding Areas and Basins

5.17.4.1 Drainage ponds, when required, shall be designed to provide sufficient capacity from the contributing drainage area equivalent of both the volume of stormwater generated by a one percent probability (100-year return frequency) storm event, and a ten-year accumulation of silt. In special circumstances, a lesser capacity may be authorized by the Horizon City Director of Public Works provided alternative means are provided to pass the design storm without causing injury, a hazard or a public nuisance. All calculations shall be made by a professional engineer registered to practice in the State of Texas, and shall be subject to review and approval by the City Engineer.

5.17.4.2 Drainage ponds shall be designed to facilitate maintenance. When ponds are not otherwise accessible by equipment from adjoining paved surfaces, access roads, not less than ten feet in width and not steeper than ten percent grade, shall be provided giving access to the base of drainage ponds from public streets. The dimensioning of ponds shall provide adequate space for the maneuvering of trucks and equipment as may be deemed appropriate by the City’s Director of Public Works and City Engineer. A permanent monument shall be placed at the base of the drainage pond to provide a benchmark for referencing the invert elevation of the drainage pond. Said monument shall be shown on the engineering plans for the drainage pond construction.

5.17.4.3 Appropriate measures shall be taken in both the drainage pond design and construction to minimize erosion potential. Such measures shall be determined by the City Director of Public Works and City Engineer. At minimum, the design and construction of drainage ponds shall provide for the following:

1. Site grading and perimeter control measures shall be used to prevent uncontrolled inflow into drainage ponds; stormwater inflow shall only be permitted via reinforced concrete drainage flumes or stormwater drainage pipes.

2. At all points of stormwater discharge into drainage ponds, velocity dissipaters shall be provided, based on good engineering practice.

3. The base of all inflow structures and all side slopes shall be compacted to a density of not less than 90 percent, based on the standards of the American Association of State Highway and Transportation Officials (AASHTO).

4. The maximum steepness of side slopes of drainage ponds shall be a ratio of two units in the horizontal for every one unit of vertical elevation change; the Director of Public Works shall be authorized to permit steeper side slopes only if a soils engineer certifies that such steeper slopes do not exceed the angle of repose of the native soil.

5. If, in the opinion of the City Director of Public Works or City Engineer, soil conditions present an erosion risk, even when properly compacted, armoring of all or any portion of the side slopes of drainage ponds shall be required. Suitable armoring or other slope stabilization may be provided by reinforced concrete, riprap, rock riprap, soil cement, or other like material.

6. The City will allow and does encourage the maintenance of existing, native plants along the side slopes as an erosion control strategy.

5.17.4.4 To provide for public safety and ensure compatibility with adjoining development, perimeter treatment shall be required for all drainage ponds. The following criteria shall govern perimeter treatment unless the developer can demonstrate that alternative means will provide equal or superior protection to the public interest:

1. All ponds dedicated to the public shall be enclosed by a six-foot high masonry wall. Such walls shall be constructed at the time drainage ponds are developed, without regard to the timing of construction of buildings on adjoining properties.

2. Access to enclosed ponds shall be provided by a wrought iron gate or a steel gate of similar appearance. A locking mechanism for the gate shall be provided in accordance with criteria to be specified by the Director of Public Works.

3. Five-foot wide concrete sidewalks shall be provided adjacent to the rock walls along all perimeter boundaries of drainage ponds that abut public street rights-of-way.

4. The parkways lying between required sidewalks and street curbing shall receive landscape treatment consisting of chat materials and, whenever possible, suitable desert plantings. Any plant materials so employed must be sufficiently drought-tolerant so as not to require supplemental irrigation.

5. When site conditions so permit, existing, native plants are not to be disturbed along the perimeter of drainage ponds so as to provide a visual buffer from other nearby development. This provision is not meant to apply to the base of the ponding areas from which all plant materials are to be removed.

5.17.4.5 The use of park areas as drainage ponds is discouraged, but may be permitted under conditions where neither use impairs the other, and where the siting and dimensioning of the park is appropriate based on good planning practices and in accordance with such plans and policies that may be adopted regarding outdoor public recreation. The application of these principles shall be solely vested in the Planning and Zoning Commission and City Council. The burden shall be on the developer to demonstrate that the combining of both park and drainage ponding usage is appropriate and in the public interest. The following criteria shall govern the combined use of a site for both park purposes and drainage ponding purposes:

1. Because the use of property for park purposes implies ready public access, the perimeter rock wall requirement is not applicable when park and drainage ponding areas are combined; the sidewalk and parkway landscaping requirements, however, shall remain in force.

2. No slope greater than ten units in the horizontal and one unit in vertical shall be permitted in combined park and drainage ponding areas.

3. Permanent improvements, such as playground equipment and facilities, shall be limited to those improvements that can withstand prolonged periods of inundation. Consequently, the appropriateness of combining park and drainage ponding use will be determined, in part, based on the desired, ultimate development of the park space.

4. The design of drainage inflow shall ensure that the maximum incoming stormwater velocity, under design storm conditions, will not exceed five feet per second in any area accessible to the general public. Furthermore, provisions shall be made to ensure that stormwater inflow will not cause scouring or other erosion damage to the park ground surface.

5. Site grading for combined park and drainage ponding areas shall be such that no more than 50 percent of the park will remain inundated for a period of more than 72 hours following a storm of a 10-year return frequency. Infiltration tests shall be required to demonstrate the adherence to this standard.

6. The maximum depth of standing water permitted in a combined park and drainage ponding area shall not exceed four feet.

7. Turf or other planting is desirable as plant roots maintain the friability of soil and thus facilitate infiltration. Therefore, developers are encouraged to install turf together with necessary irrigation systems based on criteria that shall be specified by the Director of Public Works.

8. Developers that choose to combine parks and drainage ponding areas may only claim credit for parkland dedication, as required by Ord. 0035 [this ordinance], when turf or other landscape materials and necessary irrigation systems are installed. Costs incurred in such site improvements shall not reduce the calculation of park area otherwise required.

9. When developers propose combining park space and ponding areas, innovative designs will be allowed and are preferred to separately impound runoff from 10-year return frequency storms and only use the park space as overflow for stormwater inflows from storms of greater magnitude.

5.17.4.6 Drainage ponding area requirements of the Horizon City [sic] are in addition to such design and permit requirement as may be imposed by the Texas Pollutant Discharge Elimination System (TPDES) program, and the Federal National Pollutant Discharge Elimination System (NPDES). In the event of a conflict between the provisions of this ordinance and either the TPDES or NPDES, the latter will supersede. Lacking a conflict in such regulatory standards, the more stringent standard will govern

5.17.4.7 The interpretation and application of the criteria in this ordinance will be based on a standard of reasonableness with regard to public health, safety and welfare. The Director of Public Works shall apply the regulations accordingly.

(Ordinance 0035 adopted 1/11/94; Ordinance 0035-011 adopted 2/10/04)

§ 5.18 FLOOD HAZARD AREAS.

If a subdivision or a portion of a subdivision is in an area that has been defined as a Flood Hazard Area by the U.S. Department of Housing and Urban Development maps, then said subdivision or portion of subdivision shall be constructed according to the Regulations passed by the City Council and by regulations set by the National Flood Insurance Program as stated in the Federal Register Vol. 41, No. 207 - Tuesday, January 26, 1988 and any amendments thereto. The City Council may, when it deems it necessary for the health, safety, or welfare of the present and future population of the area, prohibit the subdivision of any land which lies within the floodplain of any stream or drainage course.

(Ordinance 0035 adopted 1/11/94)

§ 5.19 LOT SIZE REQUIREMENTS.

5.19.1 

General Requirements

5.19.1.1 In proposed subdivisions utilizing approved public water systems and approved organized off-site wastewater facilities and there is no on-site ponding for individual lots, the minimum individual lot size shall be no less than six thousand (6,000) square feet in area.

5.19.1.2 In proposed subdivision utilizing approved public water systems and approved organized off-site wastewater facilities and there is on-site ponding for individual lots, the minimum individual lot size shall be no less than ten thousand (10,000) square feet in area.

5.19.1.3 In proposed subdivisions utilizing approved public water systems and on-site sewage disposal systems, the minimum lot size shall be one-half (1/2) acre in area.

5.19.1.4 In proposed subdivisions utilizing non-public water systems and on-site sewage disposal systems, the minimum lot size shall be no less than ten (10) acres in area.

5.19.1.5 In the event section 5.19.1.4 should be declared invalid, illegal or unenforceable by a court of competent jurisdiction and such judgment shall be upheld on final appeal, proposed subdivisions utilizing non-public water systems, shall have a minimum lot size of no less than one (1) acre in area.

5.19.2 

Lot Dimensions.

Minimum lot frontage shall be no less than 50' at and behind building front setback line on 6,000 sq. ft. lots. On remaining lots, frontage may not be less than 1/3 of the length of the lot from front to back.

5.19.3 

Lot Drainage.

Lots shall be laid out so as to provide positive drainage away from buildings and septic tank drainfields. Individual lot drainage shall be coordinated with the general storm drainage pattern for the area. Drainage shall be designed so as to avoid concentration of storm drainage water from each lot to adjacent lots.

(Ordinance 0035 adopted 1/11/94; Ordinance 0035-005 adopted 6/10/97; Ordinance 0035-009 adopted 9/10/02)

§ 5.20 MONUMENTS.

5.20.1 The subdivider shall place reference monuments in the subdivision as required herein as approved by a registered land surveyor.

5.20.2 

Size and Construction

5.20.2.1 The City survey monument shall be set in a poured-in-place, truncated concrete cone of eight (8) inches minimum diameter at the top, eighteen (18) inches minimum diameter at the bottom and shall be a minimum of thirty-six (36) inches in depth.

5.20.2.2 The monument shall be covered with a steel or cast-iron box and cover.

5.20.2.3 Details of design are shown in the attached Appendix.

5.20.3 

Monument Location

5.20.3.1 Monuments shall be installed so that all front property corners of all lots in the subdivision are within line of sight of a monument, or within sight of the line between two adjacent monuments.

5.20.3.2 Each monument shall be within line of sight of another monument.

5.20.3.3 Monuments shall be no farther than 2000.000 feet apart.

5.20.3.4 At least one (1) monument shall be placed on each horizontal curve. Two shall be placed if the point of intersection (P.I.) of the tangents leading into the curve falls outside of City right-of-way.

5.20.3.5 No fewer than two monuments shall be placed in one-street subdivisions.

5.20.4 The perimeter boundaries of a subdivision shall be monumented in the field by monuments of 2" galvanized pipe, not less than twenty-four (24) inches in length. These monuments shall be placed at all corners, except that when any such corners or points fall within a street or proposed future street, the monuments shall be placed in the site line of the street.

5.20.5 The lines of lots that extend to rivers or streams shall be monumented in the field by iron pipes at least thirty (30) inches long and seven-eighths (7/8) inches in diameter or by round or square iron bars at least thirty (30) inches long. These monuments shall be placed at the point of intersection of the river or stream lot line with a meander line established not less than twenty (20) feet back from the bank of the river of stream.

5.20.6 All corner monuments shall be properly set in the ground and approved by a registered land surveyor prior to filing of the final plat. All street monuments shall be properly set within two years of filing of final plat.

(Ordinance 0035 adopted 1/11/94)

§ 5.21 ADDRESSES - GENERAL.

It shall be the duty of the subdivider to assign addresses to each lot created within the new subdivision as set out by this section. All addresses must be approved by the Director of Public Works prior to submission of the final plat for acceptance.

5.21.1 Each lot created must be assigned a distinct address. When the new subdivision is an extension of an existing subdivision, the address sequence shall extend into the new subdivision. New addresses shall progress sequentially along each street in the manner so described in this section. The sequence shall progress in increments of four with the exception to maintain an existing sequence between two existing subdivisions. The block numbers shall follow the existing block plan for the City. Any lot that may be so configured as to have the possibility of either of two sides being a front property line, by way of being on a corner, shall have two addresses assigned as per the requirements of this section.[1]

[1] Original has this as 5.6.1.

5.21.2 The assignment of addresses shall follow the sequence as set forth in this section. New primary addresses assigned to lots on streets that run in an east-west direction shall be assigned a five (5) digit address with the odd-numbered addresses assigned to the north side of the street and even-numbered addresses assigned the south side of the street. New primary addresses assigned to lots on streets that run in a north-south direction shall be assigned a three (3) digit address with the odd-numbered addresses assigned to the west side of the street and even-numbered addresses assigned the east side of the street. When proposed streets create a change in direction of greater than forty-five (45) degrees but do not continue into a loop or circle, the sequencing of the addressing shall also change to accommodate the above-mentioned directional sequence. For example, an east-west directional street that changes direction to a north-south directional street shall change the numbering sequence from five (5) digit addresses to three (3) digit addresses. Any proposed street that continues in a loop shall be addressed starting with the closest entrance from a collector or arterial and with the required digit sequence that pertains to the beginning direction and continuing with said same sequence throughout the entirety of the street.[2]

Editor’s note–Ordinance 0035-014, adopted 3/8/05, amended the subdivision ordinance by adding section 5.6, “Addresses - General.” The ordinance already contained a section 5.6, adopted by Ordinance 0035-013. The provisions added by Ordinance 0035-014 have been included as section 5.21.

[2] Original has this as 5.6.2.

(Ordinance 0035-014 adopted 3/8/05)