CITY OF ASTORIA PUBLIC WORKS ENGINEERING DIVISION ENGINEERING DESIGN STANDARDS FOR IN-FILL DEVELOPMENT

Transcription

1 CITY OF ASTORIA PUBLIC WORKS ENGINEERING DIVISION ENGINEERING DESIGN STANDARDS FOR IN-FILL DEVELOPMENT Adopted by City Council: May 21, 2007 X:\General Eng\DESIGN STANDARDS\Engineering Design Standards for Infill Development.doc

2 X:\General Eng\DESIGN STANDARDS\Engineering Design Standards for Infill Development.doc

3 CITY OF ASTORIA ENGINEERING DESIGN STANDARDS FOR IN-FILL DEVELOPMENT The City of Astoria regularly receives applications for small developments, and in some cases it is not reasonable to apply the City s full standards for new developments. In the past, dealing with each small development on a case by case basis was time consuming for staff, and often frustrating for developers who had no basis for estimating the potential value of a proposed development without clearly defined expectations from the City. The following standards for new in-fill development are intended to reduce staff time and provide guidance to developers submitting small development proposals for review. These standards apply to new in-fill development within the urban growth boundary of the City of Astoria. In-fill development is defined as development of three residential lots or fewer. For developments resulting in more than three lots, the City s full development standards shall apply. GRADING AND EROSION CONTROL A plan for temporary slope stability and erosion control during construction is required, along with a plan for permanent slope stability, erosion control and plant establishment. A grading permit must be obtained from the Engineering Division before any site work, including clearing and grubbing, begins. If a geotechnical study is required by the City s Development Code, the study shall address both local and global slope stability, before, during and after development. Geotechnical recommendations shall include methods for maintaining slope stability during construction. All geotechnical recommendations shall be incorporated in the developer s grading permit application. Separate grading permits are required for public improvements to be constructed, and for the development of each lot. Refer to the City s Development Code for additional requirements. City of Astoria Engineering Standards for In-Fill Development Page 1

4 STREETS City-Maintained Streets Astoria Code 2.360(6) provides that the City may accept maintenance of new streets constructed in dedicated public rights of way. Streets serving in-fill developments shall be considered for acceptance only if construction is in accordance with City standards and the following conditions are met: A minimum 20-foot wide paved surface is required on all access roads, with curb both sides and sidewalk on at least one side. If additional development is anticipated by the City in the future, improvements should be positioned within the right of way to allow for future widening. If the proposed access road is not located within an existing public right of way, a minimum 40-foot wide public right of way should be dedicated. A cul-de-sac or hammerhead turnaround, with a 30-foot paved radius, is required at any dead end. A maximum profile grade of 12% will be allowed. All street runoff must be captured and directed to appropriate storm sewers, combined sewers or existing natural drainage channels as approved by the City Engineer. Non-City Maintained Streets The City will not accept maintenance of streets or access roads unless they meet all conditions listed above. However, in cases where the City determines the above standards are not feasible, the City Engineer may approve a privatelymaintained access road to serve an infill development. In this case, the following conditions shall apply: If building fire suppression is provided, and sprinklers have been approved by the Astoria Fire Marshall, the paved width of the access road may be reduced to 16 feet. A hammerhead, wye or cul-de-sac turnaround, with a 20-foot radius, shall be required at any dead end. Sidewalks are not required. The street or access road surface must be paved. A maximum profile grade of 16% is allowed. City of Astoria Engineering Standards for In-Fill Development Page 2

5 The total length of any access road with a reduced pavement width must be 400 feet or less. Access roads in excess of 400 feet must have a paved surface at least 20 feet wide. The maximum number of dwelling units served by the access road, including any existing dwelling units, shall be three. Streets serving more than three dwelling units must meet the requirements for City-Maintained streets. All runoff from new access roads must be controlled with curbing, and directed to appropriate storm sewers, combined sewers or existing natural drainage channels as approved by the City Engineer. The developer shall arrange for future maintenance and repair of the access road, through a road maintenance agreement or other legal mechanism to ensure perpetual maintenance. If the access road is located in the public right of way, the maintenance agreement shall clearly specify that the City may remove any road improvements as needed to construct, repair or maintain City utilities in the right of way. Restoration or repair of any roadway damage caused by City utility work will be the responsibility of the parties to the maintenance agreement. In areas where additional development is anticipated by the City, a Citymaintained standard street may someday be needed. Therefore, if a non- City maintained access road is permitted within a public right of way, the developer must execute a non-remonstrance agreement for future street improvements. Covenants may be placed on lots within the development so that this responsibility passes to subsequent owners. Street improvements constructed in the public right of way shall be positioned to allow for future widening, if additional development is anticipated by the City. Access to Neighboring Properties Construction of new street improvements within existing public rights of way shall not block access to existing homes or undeveloped property. On-Street Parking On-street parking standards for City-maintained or non-city-maintained streets are as follows: Paved Street Width Parking Configuration 20 feet or less No parking 20 to 28 feet Parking one side 28 feet or more Parking both sides City of Astoria Engineering Standards for In-Fill Development Page 3

6 Where required by the City, streets shall be posted with no-parking signs provided and installed by the developer. Signs and their locations shall be approved by the City Engineer prior to installation. Signs and Pavement Markings Any street signs and pavement markings required by the City Engineer shall be provided and installed by the developer. Street Standard Exceptions Exceptions will be granted only after review and approval of the City Engineer. Exceptions to road grade and width may be considered on a case by case basis, and require City Fire Marshall concurrence in addition to City Engineer approval. Any street width exception will require approved fire suppression systems to be installed in structures to be accessed. Plans Detailed drawings of proposed new streets or access roads must be provided to the Engineering Division for approval prior to construction. Drawings must meet the plan submittal requirements outlined below. WATER The City will accept new water facilities installed within dedicated street rights of way provided they are constructed in accordance with City standards. Water mains shall be installed beneath asphalt surfacing or unimproved portions of the right of way, and shall not run longitudinally beneath curbs or sidewalk. Water meters will be installed in the public right of way, typically at the property line. At least one hydrant shall be located within 250 unobstructed feet of each occupiable structure, or as otherwise required by the City Fire Marshall. Required fire flows are determined by the City Fire Marshall. Refer to the Oregon Fire Code for applicable fire standards related to development. As a rule of thumb, a minimum fire flow of 1,000 gallons per minute for a twohour duration is typically required for residential areas with homes containing 3,600 square feet of floor space or less. A minimum fire flow of 1,500 gallons per minute for a two-hour duration is required for residential areas with homes containing of 3,600 square feet of floor space or more. (The floor space is the City of Astoria Engineering Standards for In-Fill Development Page 4

7 sum total of all interior floor levels, excluding garage.) Other requirements may apply on a case-by-case basis as determined by the Fire Marshall. Detailed drawings of proposed water facilities must be provided to the Engineering Division for approval prior to construction. Drawings must meet the plan submittal requirements outlined below. STORM WATER MANAGEMENT A stormwater management plan shall be provided for every development. Runoff calculations and pipe sizing performed by a registered engineer may be required by the City Engineer, and shall be based on anticipated build-out. All future anticipated impervious surfaces in the development such as streets, walkways, driveways, roofs, patios, etc. shall be accommodated when designing storm water improvements. In areas where storm sewers exist within 200 feet of the proposed development, or when otherwise required by the City Engineer, the storm sewer shall be extended by the developer to serve the new development. The City will accept maintenance of new storm sewers installed within dedicated street rights of way, provided that construction is in accordance with City standards. In areas where public sanitary and storm sewers are combined, stormwater may be directed to the combined sewer system only with the approval of the City Engineer. Storm water and sanitary sewer originating on private lots shall be piped separately to the property line. At the property line, storm and sanitary sewer lines may be joined and then connected to the public combined sewer line with a single sewer lateral. Street runoff in combined-sewer areas shall be captured and routed to an existing sewer manhole. Runoff from streets and other impervious surfaces may not be directed to the surface of the ground or to a natural drainage channel, without prior approval of the City Engineer. If approved, runoff directed to natural drainage channels shall be pre-treated using a pollution control structure or biofiltration method. Rip rap or other energy dissipation facilities may be required at stormwater discharge points to prevent erosion. Detailed drawings of proposed storm sewer facilities must be provided to the Engineering Division for approval prior to construction. Drawings must meet the plan submittal requirements outlined below. City of Astoria Engineering Standards for In-Fill Development Page 5

8 SEWER The City will accept new sewer mains installed within dedicated street rights of way, provided they are constructed in accordance with City standards. Detailed drawings of proposed new public sewer lines must be provided to the Engineering Division for approval prior to construction. Drawings must meet the plan submittal requirements outlined below. PLAN SUBMITTAL REQUIREMENTS Three sets of plans shall be submitted for review. A plan sheet size of 24 X 36 is preferred. The City Engineer may accept 11 x 17 sheets for less complex proposals, provided adequate detail can be clearly shown. A scale of one inch equals twenty feet (1 =20 ) is preferred; one inch equals forty feet (1 =40 ) and one inch equals ten feet (1 =10 ) are also acceptable. Other scales may be used only with the approval of the City Engineer. The following general items shall be shown on all plan sets submitted: Vicinity Map on first sheet of set. Title block including project name, design engineer, sheet number, date and revision block. Professional Engineer s stamp (Oregon registration required.) North arrow on each sheet. Elevations shall be referenced to the City of Astoria datum or NGVD with benchmarks identified on the plans. Grading, and Erosion Control plans shall meet current City Development Code requirements. The following information shall be shown on the plans: Property lines Existing improvements (roads, buildings, retaining walls), including improvements located on adjacent properties within 25 feet of the development site. Areas where clearing, grading excavating, stripping or filling is to occur. City of Astoria Engineering Standards for In-Fill Development Page 6

9 Location of any springs, streams, wetland areas on or immediately adjacent to the property. General direction of slopes with slope arrows showing direction of water flow on existing slopes and graded slopes; depth of proposed cuts and fill. (In some cases, existing and proposed contours of the property at two-foot intervals are required by the Development Code.) Construction access Soil stockpile location. Design details for proposed retaining walls. Direction of drainage flow. Location and design details for all temporary and permanent erosion control measures and any proposed surface and subsurface drainage devices. Street Plans shall have both plan view and profile on the same sheet, and shall contain the following information: Right-of-way, property lines, and easements. Street centerline with stationing. Horizontal curve data for centerline, curb returns, cul-de-sacs and turnarounds. Curb/gutter elevations at intersections and cul-de-sacs or turn-arounds. Locations of existing underground and overhead utilities, roadways, driveways, sidewalks, structures, watercourses, survey monuments, fences and vegetation within the right-of-way and outside right-of-way, if affected by construction. Storm drainage facilities with station and offset referenced to street centerline. Existing contours and spot elevations, cut/fill limits, construction easements. Sidewalk ramp locations. City of Astoria Engineering Standards for In-Fill Development Page 7

10 Street centerline profile with tangent grades, vertical curves and high/low points. Original ground at centerline. Proposed and existing storm drainage facilities with information on type, inverts, rim/grate elevations, slopes, pipe material and trench backfill. Continuation of profile 200 feet beyond project limits if street is being reconstructed or if the City determines it may be extended in the future. Water plans shall have plan and profile views on the same sheet, and shall contain the following information: Right-of-way, property lines, and easements, including construction easements. Pipe centerlines with stationing and reference to street stationing where appropriate. Water main and service pipe materials, length, depth, pipe thrust restraint mechanisms, and trench backfill. Location of existing underground and overhead utilities, roadways, driveways, sidewalks, structures, watercourses, survey monuments, fences and vegetation within the right-of-way and outside right-of-way, if affected by construction. Existing contours and spot elevations. Original ground at pipe centerline. Proposed and existing valves and fittings, including material type and manufacturer. Existing and proposed water, storm, gas, power, cable and other utility crossings. Show separation requirements where appropriate. Sewer and Storm Sewer plans shall have plan and profile views on the same sheet, and shall contain the following information: Right-of-way, property lines, and easements, including construction easements. Pipe centerlines with stationing and reference to street stationing where appropriate. City of Astoria Engineering Standards for In-Fill Development Page 8

11 Sewer lateral pipe material, length, invert elevation and slope. Location of roadways, driveways, sidewalks, structures, watercourses, survey monuments, fences and vegetation within the right-of-way and outside right-of-way, if affected by construction. Existing and proposed water, storm, gas, power, cable and other underground or overhead utility locations. Show vertical and horizontal separation distances between water and sewer lines. Existing contours and spot elevations. Sewer invert profile with grades. Original ground at pipe centerline. Proposed and existing manholes, catch basins, field drains and area drains, with information on type, inverts, rim elevations, slopes, manhole and pipe material and trench backfill. Continuation of profile 200 feet beyond project limits if the City determines sewer may be extended in the future. STATE AND FEDERAL PERMITS Developers are responsible for obtaining any necessary state and federal permits that may be required for construction near wetland areas, streams or other waterways, or if hazardous materials are present on the property. The following agencies should be contacted to determine if state or federal permitting regulations apply: Department of State Lands (503) Department of Environmental Quality (800) US Army Corps of Engineers (503) CONSTRUCTION INSPECTION / COORDINATION The Engineering Division will need to observe the following work, and must be called at least 2 working days in advance to schedule an inspection: Installation of new storm and sanitary sewer systems, and new water facilities. City of Astoria Engineering Standards for In-Fill Development Page 9

12 Connections to existing storm and sanitary sewers, and existing water facilities. Forms for concrete curb, gutter and sidewalk Roadway subgrade, crushed rock base course and asphalt paving The developer should notify Engineering at if a pre-construction meeting for site work is scheduled so that we can attend. The Operations Division ( ) must be contacted to open or close any water valves. Subgrade and base rock compaction tests should be performed by an independent testing laboratory during construction, and results provided to the Engineering Division. FINAL ACCEPTANCE Astoria Code 2.360(6) provides for acceptance of new street facilities by City Council. Only improvements that have been constructed in accordance with City standard specifications and inspected and approved by the City Engineering Division shall be recommended for Council acceptance by the City Engineer. Upon City Council approval, the City will provide a formal letter of acceptance. The City will not maintain or repair any facilities until they have been formally accepted. Once the improvements are complete, the developer must provide a letter requesting acceptance along with as-built drawings of the street, sewer, water and storm facilities. Asbuilt drawings should be provided in electronic AutoCADcompatible format as well as hard copy. Please note: Water service will not be initiated prior to City Engineer approval of as-built drawings. Private lot development may proceed while public improvements are under construction, however, no certificates of occupancy will be issued before asbuilt drawings for street, sewer, water and storm facilities have been approved by the City Engineer. City of Astoria Engineering Standards for In-Fill Development Page 10