§ 17.5.035 STANDARDS.

   The following standards are to be met when the subject site contains natural resource areas . In order of preference, these natural resource areas are to be avoided when development as allowed by the underlying zone district can be achieved outside the area or through alternative site design allowed by a planned development ; minimize intrusion into the area to the extent feasible; or mitigate impacts from intrusions where no feasible alternatives exists. The following standards shall apply to achieve these avoid, minimize or mitigate objectives. As an alternative, the applicant may submit for discretionary approval pursuant to § 17.5.040:

   A.   Methods for avoiding or minimizing disturbance in Natural Resource Areas . The following habitat-friendly development practices may be used to avoid or minimize development within NRAs by allowing flexible site design:

      1.   Building  setback flexibility to avoid, or minimize, development within NRAs. The minimum building  setback of the base zone may be reduced to any distance between the base zone minimum and zero, unless this reduction conflicts with applicable fire or life safety requirements;

      2.   Flexible landscaping requirements to avoid, or minimize, development within NRAs.

         a.   Landscaping requirements, apart from those required for parking lots or street  berms , may be met by preserving the NRA.

         b.   Facilities that infiltrate stormwater onsite, including the associated piping, may be placed within the NRA so long as the forest canopy and the areas within the drip lines of the trees are not disturbed. Such facilities may include, but are not limited to, vegetated swales, rain gardens, vegetated filter strip and vegetated infiltration basins. Only native vegetation may be planted in these facilities.

      3.   Flexible Site Design (On-site  Density Transfer ) to avoid or minimize development within NRAs.

         a.   Residential. For residential development , up to 100% of the development that could be allowed on lands within a natural resource areas can be transferred to other portions of the property outside the resources area.

         b.   In order to accommodate the transferred density , dimensional standards and lot sizes may be adjusted by no more than 20%.

         c.   Commercial and industrial developments shall avoid natural resource areas unless no other practicable alternative is available.

         d.   Mixed-Use Zones. Within mixed-use zones, the density transfer credit can be factored using either a. or b. above, depending on the type of development proposed.

      4.   Site capacity incentives. The following site capacity standards provide flexibility in the design of land divisions in order to allow ways to better protect NRAs.

         a.   Density bonus if NRA is protected. In the Multi-Family (RMH) Residential Zone District, a 25% density bonus over the based density may be allowed for any development of four or more dwelling units if 75% or more of the NRA on a site is permanently preserved.

         b.   All area within a NRA, or any portion of it, may be subtracted from the calculations of net size for purposes of determining minimum density provided that such area is protected. This provision may only be applied to properties that were inside the Metro UGB on January 1, 2002.

         c.   Projects can be developed below minimum density allowed by the zone district if the natural resource area is protected. This provision may only be applied to properties that were inside the Metro UGB on January 1, 2002.

      5.   All natural resource areas that are preserved shall be permanently restricted from development and maintained for habitat functions, such as by making a public dedication or executing a restrictive covenant.

   B.   Development within NRA. The following development standards apply to all development that occurs within the NRA except for exempt uses and conditioned activities addressed in § 17.5.015 and utility facilities addressed in § 17.5.035C. If all development occurs outside of an NRA on a property, these standards do not apply. These standards also do not apply to development that occurs pursuant to the standards established by the alternative discretionary development standards in § 17.5.040.

      1.   Disturbance area limitations to minimize impact to NRA.

         a.   Single-family residential. The maximum disturbance area (MDA) allowed within NRAs is determined by subtracting the area of the lot or parcel outside of Habitat Conservation Area (HCA) from the total disturbance area (TDA) calculated as described in Table 5-1 below.

               (TDA – Area outside the HCA = MDA)

            i.   Moderate and Low HCAs are subject to the same disturbance area limitations.

            ii.   Calculation of maximum disturbance area. If a lot or parcel includes both High and Moderate/Low HCAs then:

                (1)   If there is more High HCA than Moderate/Low HCA on the lot or parcel, then the MDA shall be calculated as if all of the Moderate/Low and High HCA were High, per Table 5-1 below; or

               (2)   If there is more Moderate/Low HCA than High HCA on the lot or parcel, then the MDA shall be calculated as if all of the Moderate/Low and High HCA were Moderate/Low, per Table 5-1 below.

            iii.   Location of MDA. If a lot or parcel includes different types of HCAs, then:

               (1)   The amount of development that may occur within the High HCA is equal to the total disturbance area minus the area of the lot or parcel outside of the High HCA (TDA – non-High HCA = MDA). If the area of the lot or parcel outside the High HCA is greater than the total disturbance area, then development shall not occur within the High HCA:

            (Area outside High HCA > TDA = no development in High HCA);

               (2)   The amount of development that may occur within the Moderate HCA is equal to the total disturbance area minus the area of the lot or parcel outside of the High and Moderate HCA (TDA – (Low HCA + non-HCA) = MDA). If the area of the lot or parcel outside the Moderate HCA is greater than the total disturbance area, then development shall not occur within the Moderate HCA:

            (Area outside Moderate HCA > TDA = no development in Moderate HCA); and

               (3)   The amount of development that may occur within the Low HCA is equal to the total disturbance area minus the area of the lot or parcel outside of the High, Moderate and Low HCA (TDA – non-HCA = MDA). If the area of the lot or parcel outside the Low HCA is greater than the total disturbance area, then development shall not occur within the Low HCA:

            (Area outside Low HCA > TDA = no development in Low HCA).

 

Table 5-1: Total Disturbance Area Limitations for Single-Family Residential Zone Districts
HCA Type	Habitat Type	Total Disturbance Area (TDA)
High	Class I	50% of the lot area , up to maximum of 5,000 square feet
Moderate/Low	Class II	65% of the lot area , up to maximum of 6,000 square feet
Moderate/Low	Uplands Class A and B for properties brought into the UGB after January 5, 2006	65% of the lot area , up to maximum of 6,000 square feet
No HCA or NRA	Uplands Class A and B within the UGB as of January 5, 2006	N/A

 

         b.   All other zones. The maximum disturbance area (MDA) allowed by right within Natural Resource Areas in these zones is found in Tables 5-2 and 5-3 below; this MDA is subject to the mitigation requirements described in § 17.5.035D.

 

Table 5-2: NRA Disturbance Area Limitations for Riparian Areas For All Zones Other Than SFR
Riparian Class and Zone District	Maximum Disturbance Area (MDA)
Class I – RML, RMH, CC, CN, LI, GI	10% of NRA on site
Class I – CBD, RMH Class II – RML, RMH	15% of NRA on site
Class II - CC, CN, LI, GI	50% of NRA on site

 

 

Table 5-3: NRA Disturbance Area Limitations for Upland Areas For All Zones Other Than SFR
Upland Class and Zone District for property brought into UGB after January 5, 2006[1]	Maximum Disturbance Area
Class A: CC, CN, CH, LI, GI Class B: RML, RMH	15% of NRA on site
Class A: CBD Class B: CC, CN, LI, GI	50% of NRA on site
[1] There is no uplands classification for lands within the UGB as of January 5, 2006.

 

         c.   Parks and open space .

            i.   Publicly owned property designated for open space or for habitat on the city ’s Park, Recreation and Open Space Master Plan shall be limited to vegetation removal for trail development . Any other vegetation removal shall be mitigated by replanting consistent with this section.

            ii.   Parks intended for active recreational purposes as designated on the city ’s Park, Recreation and Open Space Master Plan shall not be considered in an NRA.

         d.   Development within an NRA in accordance with the provisions of this Code shall not result in a change of the NRA status of such developed areas on a property. In the case of a later development request seeking to develop within previously undisturbed NRAs on a property where a prior development request was subject to the provisions of this Code, the calculation of the MDA allowed on the property shall be based on the location of the NRA, notwithstanding the location of any authorized development within the NRA.

      2.   Protection of habitat during site  development . During development of any site containing a NRA, the following standards apply.

         a.   Work areas shall be marked to reduce potential damage to the NRA.

         b.   Trees in NRAs shall not be used as anchors for stabilizing construction equipment.

         c.   Native soils disturbed during development shall be conserved on the property.

         d.   An erosion and sediment control plan is required and shall be prepared in compliance with requirements set forth by Clean Water Services Design and Construction Standards;

         e.   Prior to construction, the NRA that is to remain undeveloped shall be flagged, fenced, or otherwise marked and shall remain undisturbed.

         f.   All work on the property shall conform to the Construction Management Plan described in § 17.5.030.

   C.   Utility facility standards. The following disturbance area limitations apply to new utilities, private connections to existing or new utility lines, and upgrade

      1.   The disturbance area for utility facility connections to utility facilities is no greater than ten feet wide.

      2.   The disturbance area for the upgrade of existing utility facilities is no greater than 15 feet wide.

      3.   The disturbance area for new underground utility facilities is no greater than 25 feet wide and disturbs no more than 200 linear feet of Water Quality Resource Area, within any 1,000 linear foot stretch of Water Quality Resource Area; provided that this disturbance area shall be restored with the exception of necessary access points to the utility facility.

      4.   No fill or excavation is allowed within the ordinary high water mark of a stream, unless a permit is obtained from the U.S. Army Corps of Engineers through the Standard Local Operating Procedures for Endangered Species (SLOPES) process.

      5.   Mitigation is required as described in § 17.5.035D. below.

   D.   Mitigation requirements for disturbance in NRAs. In order to achieve the goal of reestablishing forested canopy that meets the ecological values and functions described in this Chapter, tree replacement and vegetation planting are required when development intrudes into a NRA according to the following standards, except for wetlands  mitigation requirements imposed by state and federal law.

      1.   Required plants and plant densities. All trees , shrubs and ground cover must be native plants selected from the Metro Native Plant List. An applicant must meet Mitigation Option 1 or 2, whichever results in more tree plantings; except that where the disturbance area is one acre or more, the applicant shall comply with Mitigation Option 2:

         a.   Mitigation Option 1. In this option, the mitigation requirement is calculated based on the number and size of trees that are removed from the site . Trees that are removed from the site must be replaced as shown in Table 5-4. Conifers must be replaced with conifers. Bare ground must be planted or seeded with native grasses or herbs. Non-native sterile wheat grass may also be planted or seeded, in equal or lesser proportion to the native grasses or herbs.

 

Table 5-4: Tree Replacement
Size of tree to be removed (inches in diameter)	Number of trees and shrubs to be planted
6 to 12	2 trees and 3 shrubs
13 to 18	3 trees and 6 shrubs
19 to 24	5 trees and 12 shrubs
25 to 30	7 trees and 18 shrubs
Over 30	10 trees and 30 shrubs

 

         b.   Mitigation Option 2. In this option, the mitigation requirement is calculated based on the size of the disturbance area within a NRA. Native trees and shrubs are required to be planted at a rate of five trees and 25 shrubs per every 500 square feet of disturbance area. Bare ground must be planted or seeded with native grasses or herbs. Nonnative sterile wheat grass may also be planted or seeded, in equal or lesser proportion to the native grasses or herbs.

      2.   Plant size. Replacement trees must be at least one-half inch in caliper , measured at six inches above the ground level for field grown trees or above the soil line for container grown trees (the one-half inch minimum size may be an average caliper measure, recognizing that trees are not uniformly round), unless they are oak or madrone which may be one gallon size. Shrubs must be in at least a one-gallon container or the equivalent in ball and burlap and must be at least 12 inches in height.

      3.   Plant spacing.  Trees shall be planted between eight and 12 feet on-center and shrubs shall be planted between four and five feet on center, or clustered in single species groups of no more than four plants, with each cluster planted between eight and ten feet on-center. When planting near existing trees , the drip line of the existing tree shall be the starting point for plant spacing measurements.

      4.   Plant diversity. Shrubs must consist of at least two different species. If ten trees or more are planted, then no more than 50% of the trees may be of the same genus.

      5.   Location of mitigation area. All vegetation must be planted on the applicant ’s site within the NRA or in an area contiguous to the NRA; provided, however, that if the vegetation is planted outside of the NRA then the applicant shall preserve the contiguous area by executing a deed restriction, such as a restrictive covenant.

      6.   Invasive vegetation . Invasive non-native or noxious vegetation must be removed within the mitigation area prior to planting.

      7.   Tree and shrub survival. A minimum of 80% of the trees and shrubs planted shall remain alive on the fifth anniversary of the date that the mitigation is completed.

      8.   Monitoring and reporting. Monitoring of the mitigation  site is the ongoing responsibility of the property owner. Plants that die must be replaced in kind. For a period of five years, the property owner must submit an annual report to the Community Development Department documenting the survival of the trees and shrubs on the mitigation  site .

      9.   To enhance survival of the mitigation plantings, the following practices are required.

         a.   Mulching. Mulch new plantings a minimum of three inches in depth and 18 inches in diameter to retain moisture and discourage weed growth.

         b.   Irrigation. Water new plantings one inch per week between June 15 and October 15 for the three years following planting.

         c.   Weed control. Remove, or control, non-native or noxious vegetation throughout maintenance period.

      10.   To enhance survival of tree replacement and vegetation plantings, the following practices are recommended:

         a.   Planting season. Plant bare root trees between December 1 and February 28, and potted plants between October 15 and April 30.

         b.   Wildlife protection. Use plant sleeves or fencing to protect trees and shrubs against wildlife browsing and resulting damage to plants.

   E.   Standards for partitions and subdivisions . The purpose of this section is to allow for partitions in a manner that limits the total amount of allowable development within NRAs on the partitioned parcels; and to require that new subdivision  plats delineate and show the Moderate and High NRAs as a separate unbuildable tract.

      1.   Standards for partitions containing NRAs.

         a.   When partitioning a property into parcels, an applicant shall verify the boundaries of the NRA on the property according to § 17.5.050.

         b.   Applicants who are partitioning, but are not simultaneously developing their property, do not need to comply with § 17.5.030.

         c.   When partitioning a property into parcels there shall be no more than a 30 percentage point difference in the percentage of NRA on the parcels; for example, a partition that produces two parcels, one that is 55% NRA and the other that is 35% NRA is permissible; whereas a partition that produces two parcels, one that is 75% NRA and the other that is 30% NRA is not permissible. However, an applicant may partition a property such that at least 90% of the original property’s High NRA and 80% of its moderate NRA is on a separate unbuildable parcel, protected by a restrictive covenant or a public dedication .

         d.   Subsequent development on any parcels containing NRAs shall comply with § 17.5.030, and the development standards of either §§ 17.5.035 or 17.5.040.

      2.   Standards for subdivisions .

         a.   Applicants who are subdividing, but not developing, must verify the location of the NRA boundary according to § 17.5.050 of these provisions, and comply with this § 17.5.035E.; such applicants do not need to comply with § 17.5.030. Applicants who are sub-dividing, but not developing, property may:

            i.   Complete the mitigation requirements of § 17.5.035D. and thereby exempt all subsequent development on lots containing NRA from further review under this Code; or

            ii.   Not complete the mitigation requirements of § 17.5.035D., thus requiring that any subsequent development within an NRA be subject to this Code.

         b.   Applicants who are subdividing and developing properties must comply with §§ 17.5.030, 17.5.035 and 17.5.050.

         c.   When a property containing any NRA is subdivided, this Code requires that new subdivision  plats delineate and show 80% of the NRA as a separate unbuildable tract according to the following process:

         d.   If the tract is adjacent to the backyard for residences, the minimum backyard requirement is reduced to ten feet.

         e.   The standards for land divisions in Moderate and High NRAs shall apply in addition to the requirements of the city /county land division ordinance and zoning ordinance.

         f.   Prior to preliminary plat approval, the NRA shall be shown as a separate tract, which shall not be a part of any lot used for construction of a dwelling unit.

         g.   Prior to final plat approval, ownership of the NRA tract shall be identified to distinguish it from lots intended for sale. The tract may be identified as any one of the following:

            i.   Private natural area held by the owner or homeowners association by a restrictive covenant; or

            ii.   For residential land divisions, private natural area subject to an easement conveying storm and surface water management rights to the city and preventing the owner of the tract from activities and uses inconsistent with the purpose of this Code; or

            iii.   At the owner’s option, public natural area where the tract has been dedicated to the city or other governmental unit, or a private nonprofit with the mission of land conservation.

(Ord. 2009-01, passed 3-9-2009)