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ECO-3       Protecting Our Soil, Water & Air

Erosion & Sediment Control Training & Site Supervision

20.25H.110City of Bellevue Performance standards for Sensitive Areas.

All use and development within Sensitive Areas shall conform to the standards of this section. Standards shall apply to the entire contiguous parcel owned or controlled by the applicant if necessary to enable compliance with the purpose and intent of the Code.
A.Area of Special Flood Hazard.
1.Restricted Use and Development. No use, development or activity may occur in an Area of Special Flood Hazard except as specifically allowed by this Part 20.25H. All use, development or activity which is allowed is subject to the performance standards of this subsection. No alteration of the flood carrying capacity, configuration or volume of the Area of Special Flood Hazard is permitted except as specifically permitted by this Part 20.25H.
2.Existing Development Declared Legal Nonconforming. All development within the Area of Special Flood Hazard, LUC 20.50.010, constructed or for which a vested Building Permit application exists prior to the effective date of this Part 20.25H and which fails to comply with the requirements of this Part 20.25H is legal nonconforming development. Any change to a legal nonconforming development is subject to the performance standards of this subsection.
3.Review Required.
a.In order to assure that proposed development will be safe from flooding, the Director of Planning and Community Development and the Fire Marshal shall review and must approve, approve with conditions or deny new development under this Part 20.25H and the substantial improvement of existing development within the Area of Special Flood Hazard. The Director of Planning and Community Development shall determine that all necessary permits have been obtained from federal, state, or local agencies prior to approval.
b.The Director of Planning and Community Development shall obtain and transmit to the Director of the Utilities Department the elevation in relation to mean sea level of the lowest habitable floor, including basement, of a new or substantially improved structure permitted by this part.
c.The Director of the Utilities Department shall review and must approve all plans and specifications for new or replacement water and sanitary sewage systems permitted by this Part 20.25H to assure compliance with the regulations of this part and to assure that all necessary permits have been received from those governmental agencies from which approval is required by federal or state law or agency regulation.
4.Definitions. The following definitions apply to the Area of Special Flood Hazard regulated under this subsection:
a.Flood or Flooding. A general and temporary condition of partial or complete inundation of normally dry land areas from:
i.The overflow of inland or tidal waters; or
ii.The unusual and rapid accumulation or runoff of surface waters from any source.
b.Flood Insurance Rate Map. The map delineating special flood hazard areas effective December, 1978, that was prepared by the Federal Insurance Administration for the City or as subsequently revised by the Federal Emergency Management Agency.
c.Floodproofing. Any combination of structural and nonstructural additions, changes, or adjustments to structures which reduce or eliminate flood damage to real estate or improved real property, water and sanitary facilities, structures and their contents.
d.Habitable Floor. Any floor usable for living purposes, which includes working, sleeping, eating, cooking or recreation, or a combination thereof. A floor used only for storage purposes is not a “habitable floor.”
e.One Hundred-Year Flood. The flood having a one percent chance of being equaled or exceeded in any given year as determined by customary methods of statistical analyses defined in the Utility Code, Chapter 24.06 BCC.
f.Structure. A walled and roofed building, including a gas or liquid storage tank, that is principally above ground, as well as a mobile home.
g.Substantial Improvement. Any repair, reconstruction, or improvement of a structure, the cost of which equals or exceeds 50 percent of the replacement value of the structure either, (1) before the improvement or repair is started, or (2) if the structure has been damaged, and is being restored, before the damage occurred. For the purpose of this definition, “substantial improvement” is considered to occur when the first alteration of any wall, ceiling, floor or other structural part of the building commences whether or not that alteration affects the external dimensions of the structure. The term does not, however, include either (1) any project for improvement of a structure to comply with existing state or local health, sanitary, or safety code specifications which are solely necessary to assure safe living conditions or (2) any alteration of a structure listed on the National Register of Historic Places.
5.Intrusion Allowed. In addition to the uses and activity permitted by LUC 20.25H.080, any structure may intrude over the Area of Special Flood Hazard if:
a.The intrusion is located above existing grade, and does not alter configuration of the Area of Special Flood Hazard; and
b.The intrusion is at an elevation and orientation which maintains the existing vegetation of the Area of Special Flood Hazard in a healthy condition. Solar access to vegetation must be maintained at least 50 percent of daylight hours during the normal growing season.
No pile-supported or other structural element may be located in the Area of Special Flood Hazard except as required for those uses and activities permitted by LUC 20.25H.080.
6.Construction Standards.
a.Within the Area of Special Flood Hazard, any new development permitted by this Part 20.25H and any substantial improvement of existing development which is permitted must:
i.Be designed and adequately anchored to prevent flotation, collapse or lateral movement of the structure; and
ii.Be constructed with materials and utility equipment resistant to flood damage; and
iii.Be constructed by methods and practices that minimize flood damage; and
iv.Be constructed by methods and practices that minimize disturbance of the Area of Special Flood Hazard and retain its natural character; and
v.Be designed and constructed so that electrical heating, ventilation, plumbing and air conditioning equipment and other services are elevated or otherwise located to prevent water from entering or accumulating within the components during conditions of flooding; and
vi.Be elevated at least two feet above existing grade where floodplain data or other reliable historical flooding elevations are not available. Adequacy of historical data shall be determined by the Director of the Storm and Surface Water Utility; and
vii.The cumulative effect of any proposed development adjacent to, or encroaching within, the Area of Special Flood Hazard, when combined with all other existing and proposed development, may not increase the water surface elevation of the base flood.
b.Residential Construction.
i.The substantial improvement of an existing residential structure must result in the lowest floor (including basement) elevation being at or above the elevation of the 100-year flood; and
ii.Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, unless they are designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or must meet or exceed the following minimum criteria:
(1)A minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed floor area subject to flooding must be provided, and
(2)The bottom of all openings may be no higher than one foot above grade, and
(3)Openings may be equipped with screens, louvers, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.
c.Nonresidential Construction.
i.New development permitted by this Part 20.25H or the substantial improvement of an existing nonresidential structure must:
(1)Result in the lowest floor (including basement) elevation being at or above the elevation of the 100-year flood, or
(2)Together with attendant utility and sanitary facilities, be designed so that below a point one foot above the elevation of the 100-year flood the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. Minimum floodproofing standards are contained within Sections 210.2.1 and 210.2.2 of the U.S. Army Corps of Engineers publication entitled “Floodproofing Regulations,” June 1972, or any subsequently adopted amendments thereto. Additionally, no perceptible change in the flood elevation upstream or downstream may occur and no change in the quantity, quality or velocity of flow leaving the site may occur; and
ii.Where floodproofing is utilized for a nonresidential structure, a registered professional engineer or architect shall certify that the floodproofing methods are adequate to withstand the flood depths, pressures, velocities, impact and uplift forces and other factors associated with the 100-year flood; and
iii.Nonresidential structures that are elevated, and not floodproofed, must meet the same standards for space below the lowest floor as set forth in paragraph A.4.b.ii of this section; and
iv.Applicants floodproofing nonresidential buildings shall be notified by the Director of the Storm and Surface Water Utility that flood insurance premiums will be based on rates that are one foot below the floodproofed level (e.g., a building constructed to the base flood level will be rated as one foot below that level).
7.Roads and Utilities.
a.The Director of Planning and Community Development must approve road and utility crossings within the Area of Special Flood Hazard and must find that the utility facility, system or road is an essential public utility, and that a crossing will provide essential public access or service which cannot be made feasibly in a location which is not an Area of Special Flood Hazard. The crossing must be by bridging the Area of Special Flood Hazard and designed for shared road and utility facilities in order to minimize adverse impacts. No more than one crossing may occur on a site unless required for safe emergency access; and
b.All new and replacement water supply systems must be essential public utilities and designed to minimize or eliminate infiltration or exfiltration of floodwaters into the systems; and
c.All new and replacement sanitary sewage systems must be essential public utilities and designed to minimize or eliminate infiltration or exfiltration of floodwaters into the systems and discharges from the systems into floodwaters; and
d.All on-site waste disposal systems must be essential public utilities and located to avoid impairment to them or contamination from them during flooding.
8.Subdivisions and Other Proposed New Developments.
a.All plat and short plat proposals and other proposed new developments must:
i.Be consistent with the need to minimize flood damage; and
ii.Provide for the location and construction of public utilities and facilities, such as sewer, gas, electrical, and water systems, so as to minimize flood damage; and
iii.Provide adequate drainage to reduce exposure to flood hazards.
b.All plat and short plat proposals and other new development proposals must provide 100-year flood elevation data.
9.Agricultural Uses.
a.Erosion Control measures, such as crop rotation, mulching, strip cropping and contour cultivation must be used in conformance with guidelines and standards established by the Natural Resources Conservation Service, U.S. Department of Agriculture; and
b.Areas of Special Flood Hazard must be protected from significant impacts of agricultural chemicals and pesticides as required by the Utility Code, BCC 24.06.195, and must meet the water quality standards of BCC 24.06.060K.
B.Wetlands.
1.Restricted Use and Development. No use, development or activity may occur in a wetland except as specifically allowed by this Part 20.25H. All use, development or activity which is allowed is subject to the performance standards of this subsection.
2.Agricultural Uses.
a.Erosion Control measures, such as crop rotation, mulching, strip cropping and contour cultivation must be used in conformance with guidelines and standards established by the Natural Resources Conservation Service, U.S. Department of Agriculture; and
b.Wetland areas must be protected from significant impacts of agricultural chemicals and pesticides as required by the Storm and Surface Water Utility Code, BCC 24.06.195, and must meet the water quality standards of BCC 24.06.060K.
3.Aquaculture Uses.
a.Aquaculture development must be conducted in a way which does not adversely affect the aesthetic or environmental quality of the wetland and interrelated stream habitat; and
b.Aquaculture must to the extent feasible use underwater structures for fish rearing facilities.
4.Essential Public Utilities.
a.Essential public utilities must be located, designed and constructed to minimize or where possible avoid wetland disturbance to the maximum extent feasible. Wetland area displaced must be compensated for in compliance with paragraph B.7 of this section; and
b.All construction must be designed to protect the wetland against erosion, uncontrolled drainage, restriction of ground water movement, slides, pollution, aesthetic loss, habitat disturbance, excessive excavation or fill detrimental to the environment; and
c.Upon completion of installation of essential public utilities lines, wetlands must be restored to pre-project configuration, replanted as required to re-establish native vegetation and provided with maintenance care until newly planted vegetation is established; and
d.All utility crossings must be designed for shared facilities in order to minimize adverse impacts and reduce the number of crossings.
5.Roads.
a.Essential public roads must be located, designed and constructed to minimize or where possible avoid wetland disturbance and be designed and maintained to prevent erosion and not restrict the natural movement of ground water, to the maximum extent feasible. Wetland area displaced must be compensated for in compliance with paragraph B.7 of this section; and
b.Essential public roads must be located to conform to the topography so that minimum alteration of natural conditions is necessary. The number of crossings is limited to those necessary to provide essential public access; and
c.Essential public roads must be constructed in a way which does not adversely affect the aesthetic and hydrologic quality of the wetland and interrelated stream habitat. Where feasible, crossings must be by bridging the wetland and must allow for combination with other essential public utilities; and
d.Upon completion of construction, the area affected must be restored to an appropriate grade, replanted to re-establish native vegetation and provided with maintenance care until newly planted vegetation is established.
6.Public Use and Access.
a.Pedestrian facilities must be specifically developed for interpretive, educational or research purposes, by or in cooperation with the City or as part of an adopted nonmotorized trail linkage program, or be part of a system of public or private trails as part of a development proposal or serve as access to or within an allowed use within a sensitive or protected area. Trail development shall:
i.Avoid removal or disturbance of significant trees and limit disturbance of understory vegetation,
ii.Be maintained at the minimum width necessary to accomplish their purpose and function,
iii.Consolidate opportunities for public or private access,
iv.Minimize crossings of Riparian Corridors or wetlands and utilize bridges or elevated structures where such crossings occur,
v.Incorporate design features and materials which protect water quality and allow adequate surface and ground water movements;
b.Public and private trails should be located outside protected areas except where no feasible alternative is available. If no feasible alternative exists, trails within protected areas must be located within areas which have the lowest sensitivity to human disturbance or alteration; and
c.No interpretive center may be constructed in a wetland of less than 150 acres. Additionally, an interpretive center must be located in either that portion of a wetland which is degraded or in an intermittent wetland having the lowest sensitivity to human disturbance or alteration; and
d.No motorized vehicle is allowed within a wetland or its setback required by LUC 20.25H.090 except as required for necessary maintenance, agricultural management or security; and
e.Any public access or interpretive facility developed in a wetland must, to the extent possible, be connected with a park, recreation or open-space area; and
f.Vegetative edges, structural barriers, signs or other measures must be provided wherever necessary to protect sensitive areas by limiting access to designated public use or interpretive areas; and
g.Consolidated area for nesting, breeding, and rearing must be preserved in the wetland area and its setback required by LUC 20.25H.090 to protect sensitive plant and wildlife species; and
h.Dredging or filling within a wetland may occur only for the following purposes:
i.Maintenance of an existing water body, or
ii.Enhancement or restoration of habitat in conformance with City of Bellevue standards adopted by the Director of the Department of Planning and Community Development and the Director of the Storm and Surface Water Utility, or
iii.Natural system interpretation, education or research when undertaken by, or in cooperation with, the City, or
iv.Flood control or water quality enhancement by the City of Bellevue.
7. Wetland Modification.
a.Wetlands displaced by a permitted use such as an essential public facility shall be replaced at the time of construction of the permitted uses.
b.Filling or alteration of an existing wetland and creation of a new replacement wetland is prohibited unless the site is more than 50 percent protected area and the filling or alteration is necessary to accommodate an essential element of a permitted use of the site; or the filling or alteration is necessary to provide specific site access where no feasible alternative is available. Such an alteration may be approved if the proposal:
i.Disturbs no more than 10 percent of the wetland or one acre, whichever is less; and
ii.Does not affect any habitat type which is unique in that wetland when considering the entire wetland, both on- and off-site; and
iii.Will not result in long-term adverse impact on water quality; and
iv.Does not reduce the diversity of habitat found in the wetland; and
v.Is the minimum necessary to accommodate reasonable development of the property; and
vi.The development which the wetland adjustment is proposed to accommodate incorporates the best available construction, design and development techniques which result in the least impact on the Protected Area; and
vii.The development incorporates a proposed configuration which will result in less total coverage by impervious surface than would otherwise be required for reasonable development of the property; and
viii.The wetland adjustment is not necessary because of actions by the applicant in segregating the property and creating the unusual configuration; and
ix.Does not significantly impact the hydrological relationship between the wetland and streams or lakes.
c.Plans for wetland restoration shall be prepared by a qualified wetland biologist or wetland restoration professional and approved prior to construction of the approved use.
i.Plans shall address the hydrologic, water quality, vegetation community and wildlife habitat functions of the existing wetland and the wetland to be created; and
ii.The area of the replacement wetland shall be a minimum of:
a)2 times the displaced area for Type A wetlands;
b)1.5 times the displaced area for Type B wetlands; and
iii.The replacement wetland created must replicate, to the extent feasible, the functional characteristics of the original wetland including soil, hydrology, depth, gradient, approximate shape, water quality, vegetation community and wildlife habitat functions; and
iv.The wetland primary setback for the created wetland area must provide an effective buffer equal or superior to that existing for the original wetland; and
v.Replacement wetland area shall be located within the same stream corridor as Type A displaced wetlands wherever feasible, and within the same drainage basin for all wetlands. If off-site, permanent Native Growth Protection Area designations and restrictions must be recorded with the King County Department of Records over the affected replacement area to assure long-term preservation.
d.Replacement wetlands shall be completed prior to issuance of Occupancy Permits for the displacing use; or plans must be approved with a specific schedule for completion with provision of an assurance device of at least 150 percent of the cost of installation and monitoring.
e.A monitoring plan shall be prepared to monitor successful re-establishment of the wetland for a period of three growing seasons. The applicant shall provide an assurance device in an amount necessary to retain a qualified wetlands biologist to assess the wetland and submit a report to the City at least twice yearly, prior to and near the end of the growing season and shall provide an assurance device in an amount necessary to implement additional restoration measures if the replacement wetland does not equal the functions of the wetland displaced.
C.Riparian Corridors.
1.Restricted Use and Development. No use, development or activity may occur in a Riparian Corridor or Riparian Corridor setback except as specifically allowed by this Part 20.25H. All use, development or activity which is allowed is subject to the performance standards of LUC 20.25H.110.C.
2.Essential Public Utilities.
a.Essential public utilities must be located, designed and constructed to minimize and where possible avoid Riparian Corridor disturbance to the maximum extent feasible; and
b.All construction must be designed to protect the Riparian Corridor against erosion,  uncontrolled drainage, slides, pollution, aesthetic loss, habitat disturbance, excessive excavation or fill detrimental to the environment; and
c.Upon completion of installation of essential public utilities, the Riparian Corridor must be restored to pre-project configuration, replanted with native species and provided with maintenance care until newly planted vegetation is established; and
d.All crossings must be designed for shared utilities in order to minimize adverse impacts and reduce the number of crossings.
3.Roads.
a.Essential public roads must be located, designed, constructed and maintained to minimize or where possible avoid Riparian Corridor disturbance, to prevent erosion and not restrict the natural movement of ground water to the maximum extent feasible; and
b.Essential public roads must be located to conform to the topography so that minimum alteration of natural conditions is necessary. The number of crossings is limited to these necessary to provide essential public access; and
c.Essential public roads must be constructed in a way which does not adversely affect the aesthetic and hydrologic quality of the Riparian Corridor. Where allowed, crossings of streams and floodplains in Type A and Type B Riparian Corridors shall be made by bridging to minimize adverse environmental impacts. Type C Riparian Corridors do not need to be bridged. Where feasible, roadway crossings should be combined with other essential public utilities; and
d.Upon completion of construction, the area affected must be restored to an appropriate grade, replanted as required by the Clearing and Grading Code and provided with maintenance care until newly planted vegetation is established.
4.Public Use and Access.
a.Pedestrian facilities must be specifically developed for interpretive, educational or research purposes, by or in cooperation with the City or as part of an adopted nonmotorized trail linkage program, or be part of a system of public or private trails as part of a development proposal or serve as access to or within an allowed use within a sensitive or protected area, or connected existing uses in a manner that serves to enhance pedestrian circulation and reduce vehicular trip generation. Trail development shall:
i.Avoid removal or disturbance of significant trees and limit disturbance of understory vegetation,
ii.Be maintained at the minimum width necessary to accomplish their purpose and function,
iii.Consolidate opportunities for public or private access,
iv.Minimize crossings of Riparian Corridors or wetlands and utilize bridges or elevated structures where such crossings occur. Bridges or elevated structures across Riparian Corridors must be designed so that they will not wash out during high stream flows;
b.Public and private trails should be located outside protected areas except where no feasible alternative is available. If no feasible alternative exists, trails within protected areas must be located within areas which have the lowest sensitivity to human disturbance or alteration; and
c.No motorized vehicle is allowed within a Riparian Corridor or its setback required by LUC 20.25H.090 except as required for necessary maintenance, agricultural management or security or as part of an approved recreational activity; and
d.Any public access or interpretative facility developed in a Riparian Corridor must, to the extent possible, be connected with a park, recreation or open space area; and
e.Vegetative edges, structural barriers, signs or other measures must be provided where necessary to protect sensitive areas by limiting access to designated public use or interpretive areas; and
f.Consolidated area for nesting, breeding and rearing must be reserved in the Riparian Corridor area and its setback required by LUC 20.25H.090 to protect sensitive plant and wildlife species; and
g.Dredging or filling within a Riparian Corridor may occur only for the following purposes:
i.Maintenance of an existing corridor, or
ii.Enhancement or restoration of habitat in conformance with City of Bellevue standards adopted by the Director of Planning and Community Development, or
iii.Natural system interpretation, education or research when undertaken by or in cooperation with the City, or
iv.Flood control or water quality enhancement by the City of Bellevue.
D.Sensitive Earth Conditions.
The provisions of this subsection apply to each use or development on property including a slope equal to or greater than 15 percent, including subdivisions, short subdivisions and planned unit developments. Development on individual single-family lots is exempt from the provisions of paragraph D.1 of this section (disturbance limitations), except that any restrictions on disturbance on individual single-family lots that have been imposed through subdivision, short subdivision or planned unit development approval do apply.
1.Disturbance Limitations.
a.Basic Requirement. Development on property including a slope equal to or greater than 15 percent must:
i.Consolidate all areas of disturbance on the areas of least slope; and
ii.Minimize changes in grade, cleared area and volume of cut or fill on the site; and
iii.Comply with a limitation on disturbance of the subject property calculated as set forth in the following equation:
Disturbance Equation
(sq. ft. of site 0 – 15% slope) x 100% +
(sq. ft. of site 15 – 25% slope) x 60% +
(sq. ft. of site 25 – 40% slope) x 45% +
(sq. ft. of site 40% plus slope) x 30% = Total amount of disturbance on-site allowed
 

* This chart is for illustration purposes only.
iv.For subdivisions, short subdivisions and planned unit developments, disturbance limits shall be designated on preliminary and final approvals.
2.Commercial and Multifamily Development.
a.Location.
i.Development must be located to minimize disturbance and removal of vegetation; and
ii.Structures must be clustered to retain as much open space as possible and the natural topographic character of the slope; and
iii.Structures must conform to the natural contour of the slope. The foundation must be tiered to conform to the existing topography of the site; and
iv.Development must be located so as to preserve the most sensitive portion of the site and its natural landforms or to protect vistas from public spaces.
b.Design.
i.Development must minimize the footprint of buildings and other disturbed areas. The least number of buildings is desirable in order to consolidate the development; and
ii.Development must retain consolidated areas of natural vegetation; and
iii.Development must be designed with a foundation type that is compatible with existing slope conditions and that minimizes topographic modification. Where feasible, earth retention measures should be incorporated into the structure; and
iv.Standard prepared building pads, i.e., slab on grade, resulting in grading more than 10 feet outside the building footprint area are prohibited; and
v.Development must be designed to minimize the amount of impervious surface; and
vi.Use of common access drives and utility corridors is required where feasible; and
vii.Development must be designed to minimize lot coverage and must, with the exception of detached single-family structures, incorporate under-structure parking and multilevel structures where permitted; and
viii.Roads, walkways and parking areas must be designed parallel to contours with consideration to maintaining consolidated areas of natural topography and vegetation. Access must be located in the least sensitive area feasible; and
ix.Use of retaining walls which allow the maintenance of existing natural slope areas is preferred over graded artificial slopes.
c.Construction Types.
i.Use of foundation walls as retaining walls is preferable to rock or concrete walls built separately and away from the building. Freestanding retaining devices are only permitted when they cannot be designed as structural elements of the building foundation; and
ii.Use of pole-type construction which conforms to the existing topography is required where feasible. The structure must be tiered to conform to the existing topography and to minimize topographic modification; and
iii.Change in grade, cleared area and volume of cut or fill on the site must be minimized; and
iv.Piled deck support structures are preferred for parking or garages over fill-based construction types.
3.Subdivision and Short Subdivision.
a.Location.
i.Lots which contain sensitive areas must be configured in a manner which, to the maximum extent possible, will allow a structure to be built on the least sensitive portion of the site; and
ii.Lots which contain protected area must be configured in a manner which will allow a designated building pad to be located outside of any protected area or protected area setback.
b.Design.
i.Roads must be designed parallel to contours with consideration to maintaining consolidated areas of natural topography and vegetation. Access must be located in the least sensitive area feasible; and
ii.Change in grade, cleared area and volume of cut or fill on the site must be minimized; and
iii.Utilities and other facilities should be located to utilize common corridors wherever possible; and
iv.Protected nondisturbed areas and retained significant trees should be retained in contiguous tracts, and placed in common ownership or contiguous easements whenever feasible; and
v.Management plans should be prepared for areas of retained vegetation designating future management responsibility with planting of additional vegetation required at the time of development of plat infrastructure to maintain a healthy climax community of native vegetation; and
vi.Each lot with slopes in excess of 25 percent shall demonstrate provision for feasible driveway access to a future residence not to exceed 15 percent or provide for meeting emergency access and fire protection by other means allowed by applicable codes, and shall demonstrate feasibility of construction of a residence on the lot through a design consistent with the standards of this Code. Shared driveway access and private roads should be utilized where significant reduction of grading can be accomplished compared to separate driveway access for each individual lot.
4.Single-Family Dwellings.
a.Design.
i.Design shall minimize topographic modification. Structures shall conform to the natural contour of the slope. The foundation shall be tiered to conform to the existing topography and step down the slope with earth retention incorporated into the structure where feasible. Standard prepared building pads, i.e., slab on grade shall be avoided; and
ii.Garages on sites sloping uphill should be placed below the main floor elevation where feasible to reduce grading and to fit structures into existing topography. Garages on sites sloping downhill from the street may be required to be placed as close to the right-of-way as feasible and at or near street grade. Intrusion into the front setback, as provided in LUC 20.20.025.B, may be required. On slopes in excess of 25 percent, driveways shall be designed to minimize disturbance and should provide the most direct connection between the building and the public or private street; and
iii.Changes in existing grade outside the building footprint shall be minimized. Excavation shall not exceed 10 feet. Fill shall not exceed five feet subject to the following provisions: all fill in excess of four feet shall be engineered; and engineered fill may be approved in exceptional circumstances to exceed five feet to a maximum of eight feet. Exceptional circumstances are: 1) instances where driveway access would exceed 15 percent slope if additional fill retained by the building foundation is not permitted; or 2) where the five-foot fill maximum generally is observed but limited additional fill is necessary to accommodate localized variations in topography; and
iv.Where change in grade outside the building footprint is necessary, the site retention system should be stepped and regrading should be designed to minimize topographic modification. On slopes in excess of 25 percent, grading for yard area may be disallowed where inconsistent with this criteria.
b.Construction Types.
i.Building foundation walls shall be utilized as retaining walls rather than rockeries or retaining structures built separately and away from the building wherever feasible. Freestanding retaining devices are only permitted when they cannot be designed as structural elements of the building foundation; and
ii.On slopes in excess of 25 percent, use of pole-type construction which conforms to the existing topography is required where feasible. The structure must be tiered to conform to the existing topography and to minimize topographic modification; and
iii.On slopes in excess of 25 percent, piled deck support structures are preferred for parking or garages over fill-based construction types. (Ord. 5089, 8-3-98, §§ 29, 30; Ord. 5055, 3-2-98, § 1; Ord. 4979, 3-17-97, § 17; Ord. 4974, 3-3-97, § 2; Ord. 4973, 3-3-97, § 506; Ord. 4831-C, 12-12-95, § 1; Ord. 4816, 12-4-95, § 606; Ord. 4816, 12-4-95, § 606; Ord. 4654, 6-6-94, § 52; Ord. 4302, 11-18-91, §§ 10 – 14; Ord. 3775, 5-26-87, § 18)
 
20.25H.120Recording required.

The property owner receiving approval of a use or development pursuant to this Part 20.25H shall record a site plan or other instrument clearly delineating the Protected Area designated by LUC 20.25H.070 with the King County Division of Records and Elections and with the Bellevue City Clerk.
A.Plats shall contain:
1.Protected Areas shall be designated on the face of the plat as Native Growth Protection Areas in a format approved by the City Attorney. The designation shall include the following restrictions:
a.An assurance that native vegetation will be preserved for the purpose of preventing harm to property and the environment, including, but not limited to, controlling surface water runoff and erosion, maintaining slope stability, buffering and protecting plants and animal habitat; and
b.The right of the City of Bellevue to enforce the terms of the restriction.
2.Areas designated for nondisturbance shall be designated as Retained Vegetation Areas in a format approved by the City Attorney. The designation shall include the following restriction:
a.An assurance that existing native and compatible introduced vegetation which provides overstory will be preserved for the purposes of buffering, protecting plants and animal habitat and for aesthetic and other purposes;
b.The right of the City of Bellevue to enforce the terms of the restriction.
B.The site plans must include a statement that the provisions of this Part 20.25H as now or hereafter amended control use and development of the subject property. The Director may require recording with the King County Department of Records of the delineation of, and restrictions of, Native Growth Protection Areas and Retained Vegetation Areas for development other than subdivisions. Single-family development is exempt from this recording requirement.
C.Management plans including but not limited to replanting, signing and fencing may be required for Protected Areas and nondisturbed areas to ensure maintenance of a viable community of native vegetation. (Ord. 4979, 3-17-97, § 18; Ord. 4973, 3-3-97, § 507; Ord. 4816, 12-4-95, § 607; Ord. 4302, 11-18-91, § 15; Ord. 3775, 5-26-87, § 18)
 
 

20.25H.130Assurance device.

In appropriate circumstances, the City may require a performance or maintenance assurance device in conformance with LUC 20.40.490 to assure compliance with the provisions of this part and adequate protection of a sensitive area designated by the City of Bellevue Sensitive Area Notebook. (Ord. 3775, 5-26-87, § 18)
 
20.25H.140Protected area development exception.

If more than 90 percent of a property is within a protected area designated by LUC 20.25H.070 or within a protected area setback required by LUC 20.25H.090, and if no use listed in LUC 20.25H.080.B constitutes a reasonable potential use of the property, the property owner may request a Protected Area Development Exception pursuant to Part 20.30P LUC. (Ord. 3775, 5-26-87, § 18)
 

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