Staff Report

ITEM NO. 4

MEETING DATE: 9/27/00

Address: South (upslope) side of Trestle Glen Boulevard east of its intersection with Tiburon Boulevard (PD#18A)

AP No.: 58-061-82 & 83

File No.: 39908

General Plan: L (Low Density Residential (up to 0.3 du./acre)

Zoning: RPD (Residential Planned Development Zone - up to 0.3 du./acre)

Property Size: 14.5

Subdivision: None—created by grant deed

Current Use: Undeveloped land

Owner: Edgemont, LLC

Applicant: Steve Hixson

Date Complete: October 27, 1999

SITE HISTORY

The property was once part of the greater holdings of the Little Reed Ranch owned by the heirs of John Reed. It was later part of the Bostick Brothers Dairy operation as cattle grazing land. The property was later acquired by Sam Shapero, the first Treasurer of the City of Tiburon, who had developed some of the neighborhoods above the property.

In 1973, a 54-unit townhouse project called Tiburon Towne was submitted for approval on this site and on the adjoining Tiburon Court site to the east, which were under the same ownership at that time. Approximately 12 of the 54 units would have been built on the Trestle Glen Lower portion of the site. The maximum density at the time was up to 2.5 units per acre, allowing up to 69 units on the 28-acre total site. That application was withdrawn in October 1974 for unspecified reasons.

In 1978, the property was conveyed to Cherry family, which owned it into the 1990’s. In July 1981, the owners filed a proposal for a 36-unit single family lot project called Tiburon Meadows. Approximately 23 of the 36 units would have been located on the "Lower Trestle Glen" portion of the 28 acres. The property was still zoned for up to 69 units at that time. This proposal was eventually withdrawn due to a lack of funding by the applicant to further process the application.

In 1989, the Town of Tiburon revised its General Plan and "down-zoned" the entire property from a density of 2.5 units per acre to 0.3 units per acre, allowing a maximum of 8 lots on the 28-acre Cherry Property.

In the mid-1990s the two major holdings comprising the Cherry property were sold to different buyers.

In 1997, new owners submitted an application for four single-family lots on the 14.5-acre "Lower Trestle Glen" property. The project proposed two lots deriving access from Trestle Glen Boulevard via a single driveway, and one lot each deriving access from extensions of Silverado Drive and Comstock Drive in the Little Reed Heights neighborhood at the upper reaches of the property. Both of the proposed upper lots would have been tributary to Stewart Drive.

Town staff advised the applicants that this proposal would constitute poor site planning, exacerbate serious existing access problems at Stewart Drive, and visually impact a prominent secondary ridgeline. The proposal also met stiff opposition from segments of the Little Reed Heights/Tiburon Knolls neighborhood. The property changed ownership and the new owners redesigned the proposal to avoid the most glaring site planning and access deficiencies. The current application from Edgemont, LLC was filed in December 1999 (Exhibit 1).

PROJECT DESCRIPTION

Full size and 11" X 17" reduced drawings of the proposed project as attached as Attachments 2 and 3. The Lower Trestle Glen project occupies 14.5 acres on a northwest facing hillside approximately 300 feet north from the intersection of Tiburon Boulevard and Trestle Glen Boulevard. The property extends up-slope from Trestle Glen Boulevard to a developed residential area (Little Reed Heights) located along Comstock Drive, Silverado Drive, and Stewart Drive on the ridge top. More residential lots border the site on the southwest along Trestle Glen Terrace. An undeveloped parcel (the Tiburon Court project) lies to the east of the project site. Additional residential development along Hacienda Drive lies further east of the Tiburon Court project site. The current landscape is comprised of a steep, grass-covered hillside with large areas of dense brush and scattered oak, bay, and pine trees. Hillside slopes range from approximately 5 percent near the bottom of the property to greater than 40 percent near the upper reaches of the property. Elevations range from 40 feet above mean sea level (MSL) along Trestle Glen Boulevard to approximately 300 feet MSL near the top of the ridge.

The proposed project would divide the site into four lots. Building envelopes ranging from 9,714 square feet (sf) to 13, 488 sf would be located on the lots (see Table 1). The average site coverage within each building envelope would be approximately of 3,500 sf, including the area for the homes, driveways, and aprons. The homes themselves would range in size from 5,500 to 7,500 sf. All building envelopes would have a maximum height of 30 feet. The building envelopes would be clustered at the lower, flatter portion of the site. Lots 2, 3, and 4 would contain building envelopes for accessory buildings or structures (pool house, storage, guesthouse, etc.) up-slope from the main building site. The accessory structures could be no more than 300 sf in area (approximately 15 feet by 20 feet) and no more than 15 feet in height. These accessory structures cannot be secondary dwelling units.

Table 1. Proposed Lot Development

Source: Meridian Surveying Engineering, Inc. May 15, 2000

Private Open Space

The upper portion of the site, from the 160-foot elevation to the 300-foot elevation, would remain as undeveloped open space within Lots 2, 3 and 4. This land would be designated private open space, to be maintained by individual lot owners, and covered by an open space easement. The open space easement is intended to maintain the scenic value of the open space at the upper elevations of the property by placing restrictions on its use.

Access Roadway

An access roadway would be built through the lower portion of the site to connect with Trestle Glen Boulevard. The roadway would be approximately 50 feet wide at the intersection with Trestle Glen Boulevard and would narrow to a 20-foot-wide roadway as it ascends the property. The roadway would curve up the hill for approximately 550 feet and would terminate at a "hammerhead" turnaround. This roadway would provide access to the four residential lots, either directly or via driveways extending from the roadway. Lot owners would be responsible for maintaining this private roadway under a "Common Driveway Maintenance Agreement" to be recorded after Town review and approval. The access road would be asphalt paved with asphalt curbs, and portions of it would be stabilized by concrete retaining walls. The project would dedicate a ten-foot wide strip along Trestle Glen Boulevard for future uses, including possible roadway widening, bicycle path or public access trail.

Proposed Grading and Site Stability Measures

Approximately 3.3 acres of disturbance would occur as a result of the project, or approximately 22 percent of the site. This area would be concentrated in the lower, flatter portions of the site. Areas disturbed by grading and other construction activities would be limited to access roadway construction areas, building envelopes, a construction staging area in Lot 4, utility trenches, and lot drainage, including ditches and culverts, and historic debris flows and landslide areas that exist on Lots 1 and 3. Historic debris flow and landslide remediation would be designed for the project by a project Geotechnical Engineer and reviewed by the Town of Tiburon Engineer.

Approximately 2,040 cubic yards of soil would be cut from the hillside due to site grading, roadway construction, and soil stabilization activities. Approximately 1,300 cubic yards of soil would be used as compacted fill on site, leaving approximately 740 cubic yards of excess soil that would require off-hauling. The estimated number of truck trips to remove the excess soil is 92, over an estimated time period of five to nine months.

Portions of the hillside and the access roadway would be reinforced with three concrete keystone retaining walls. Two retaining walls constructed up-slope from the roadway would be approximately 110 and 60 feet long, respectively; reaching a maximum height of up to 8.5 feet at certain points. One retaining wall constructed down-slope from the roadway would be approximately 190 feet long and reach a height of up to 11 feet in places.

Proposed Site Drainage

A concrete "V" ditch approximately 450 feet long would be constructed to intercept surface runoff from above the homes on Lots 2, 3, and 4. The V-ditch would direct runoff into a drop inlet located on the boundary between Lots 2 and 3. A new 18" diameter underground culvert would direct the flow from this drop inlet underneath Trestle Glen Boulevard and into a concrete-lined channel on the north side of Trestle Glen Boulevard. Additionally, surface runoff would be collected from the edges of building envelopes (Lots 1, 2 and 4), the up-slope portions of retaining walls, and from storm drains located on the access roadway. Runoff from these areas would be directed through an existing 18" underground culvert to Trestle Glen Boulevard. The drainage from this channel flows under Tiburon Boulevard, then through a natural channel to Richardson Bay.

Landscape Plan

New landscaping would be limited to the entry on Trestle Glen Boulevard, revegetation of the graded slopes along the access roadway, and the landscape envelopes extending beyond each building envelope. The remainder of the site would be left in its natural condition. The landscape improvements planned for the entry include decorative boulders, and a number of trees, including Italian Stone Pine (Pinus pinea), Bolleana poplar (Populus alba), and Eastern Redbud (Cercis canadensis). Shrubs planned for the entry feature would include Coffeeberry (Rhamnus californica), Pride of Madiera (Exhium fastuosum), Dwarf Coyote Brush (Baccharis pilularis), and Rosemary (Rosmarinus officianlis). Plantings along the roadway would include at least 20 Coast Live Oak (quercus agrifolia) and California Black Oak (Quercus kelloggii). Tree size would generally be in 15-gallon cans. Plantings along the roadway would also include a hydroseed mix of naturalized European grasses, as well as the same shrubs specified for the entry feature.

A landscape and fencing envelope extending a maximum of 65 feet beyond the building envelopes would encircle the development. The envelope would extend from approximately the 50-foot elevation at the lower end of the site to the 150-foot elevation at the upper end of the site. The envelope would allow residents to place landscaping, landscape features such as decorative lighting, and fencing not to exceed 6 feet in height in their respective lots. The landscape envelope is not intended to allow structures, such as decks, pools, or hot tubs.

Site Utilities

The majority of utilities (water, telephone, electricity and gas) would be placed underground beneath the access roadway and would be constructed at one time. Utilities would be placed in a trench and then backfilled. Sanitary sewer would also be placed in an underground trench, but not beneath the roadway. Separate sanitary sewer lines would run down-slope from each lot. Sanitary sewer lines for Lots 1, 2, and 3 would be combined into one trench along the property line between Lots 1 and 2. Lot 4 would have a separate trench for sanitary sewer aligned to the north of the proposed access roadway. These lines would have individual connections to a proposed new main sewer line to be constructed along Trestle Glen Boulevard to the intersection with Tiburon Boulevard.

Site Easements

Five easements encumber the site on its southeastern and southwestern boundaries. Easements extend into Lots 2, 3, and 4. The easements extending into Lot 2 are landscape and recreation easements for the adjacent residential properties. They allow for residential recreation, installation of fencing, landscaping, hot tub, decking, utilities, and retaining walls. The easements are between 9,655 square feet to 11,700 square feet in size. Fences currently enclose portions of these easement areas. The easements extending into Lots 3 and 4 are narrow utility easements associated with the residential development on the top of the ridge. None of these easements encroach onto the building envelopes of the proposed project.

New easements that would be part of the project include a 10-foot sewer and storm drain easement running between Lots 1 and 2 to Trestle Glen Boulevard, a 10-foot storm drain easement from Lot 4 to Trestle Glen Boulevard, slope easements on Lots 1, 3, and 4, and a 40-foot utility easement containing the access roadway (10-foot easements to either side of the 20-foot-wide roadway). The utility and assessment plan is on file with the Town of Tiburon Planning Department and will be on display at the meeting.

ENVIRONMENTAL REVIEW

An expanded Initial Study and draft Mitigated Negative Declaration for this project was prepared under contract to the Town of Tiburon by the consulting firm of EDAW, and released for public review and comment on August 25, 2000. Planning Commissioners received copies of the document at that time, and should refer to this document for detailed information. An additional copy of the Initial Study is attached with Commission packets for convenience (Attachment C).

The initial study synthesized the findings of numerous professionally-prepared studies, an independent geotechnical peer review commissioned by the Town of Tiburon, and in-house peer review by the Town’s environmental consultant. The studies included a cultural resources study, traffic study, preliminary geotechnical engineering investigation and independent peer review, a faunal assessment, three biological studies, an acoustical analysis, a hydrology report, and a visual simulation. These documents are available for review in the Tiburon Planning Department.

The comment period on the draft Mitigated Negative Declaration closes on September 25, 2000 but is customarily extended to include the first Planning Commission public hearing. As of this report, two letters have been received (Exhibits 2 and 3). Staff and consultants will be prepared to respond to these questions at the meeting.

The draft mitigated negative declaration identifies several environmental factors that would potentially be affected by the project. These are:

Air Quality

Biological Resources

Cultural Resources

Geology and Soils

Hazards and Hazardous Materials

Noise

Transportation and Traffic

Mitigation measures presented in the Initial Study and accepted in wiring by the applicant would reduce all potential impacts to less than significant levels. A brief discussion of each affected environmental factor is provided below.

Air Quality

Standard mitigation measures are proposed to reduce the potential dust and other air quality impacts that may occur during construction on the site. Measures include watering and sweeping of the site and streets, covering of materials, and hydroseeding of disturbed areas.

Biological Resources

Significant biological resources are located in portions of the site to be protected by a Town-held open space easement. These resources include riparian habitat, native grasslands, and oak woodland.

Cultural Resources

While it is very unlikely to occur, any discovery of subsurface cultural resources will result in a halt of the project work in the vicinity so that the proper authorities can be consulted.

Geology and Soils

As is common with hillside properties on the Tiburon Peninsula, the subject property contains areas of unstable soils in the form of landslides and debris flows. Debris flows and landslides are differentiated by the velocity at which the ground movement occurs. Debris flows are fast moving, highly fluid landslides that occur during periods of intense rainfall (i. e. mudslides). Landslides can move at a rate of only inches per day.

A preliminary geotechnical investigation was prepared for the project site as detailed in the Initial Study. This report was intensively reviewed by an independent geotechnical engineer retained by the Town of Tiburon, namely Eugene Miller of Miller Pacific Engineering, as well as by the Town Engineer.

Because soils on much of the Tiburon Peninsula are prone to instability, the Town of Tiburon has adopted stringent landslide repair policies (Exhibit 4). Landslide repairs and debris flow mitigations will be required as part of any subdivision of this property prior to the construction of individual homes. Completion of these improvements is fully bonded such that the Town can complete the work should the developer be unable to do so.

The Project Geotechnical Engineer, Town Engineer, and Town Geotechnical Consultant will ensure that the Town’s landslide repair policies are implemented on this property, eliminating or greatly reducing the potential for damage from soil instability. Decades ago, substantial landslide repair on properties in Tiburon was cost prohibitive and led to the abandonment of many development proposals. The extremely high real estate values in Tiburon over the previous 15 years now allows for complete landslide repair without rendering projects financially infeasible.

Hazards & Hazardous Materials

Susceptibility to wildland fires was identified as a potential project impact. Conformance with required provisions of the current Tiburon Fire Protection District codes will reduce potential wildland fire hazard impacts to less than significant levels.

Noise

Traffic noise along Trestle Glen Boulevard could exceed required standards for noise levels inside homes closest to the street. Windows and doors will require greater than normal sound insulation, such as double pane windows and solid core doors.

Short-term construction impacts will inevitably cause irritation and inconvenience for surrounding properties. Such impacts, while certainly annoying, do not constitute significant adverse environmental impacts under CEQA. Limited hours for construction and use of heavy equipment will reduce noise impacts to less than significant levels, especially during traditionally quiet hours and on weekends.

Transportation and Traffic

Adequacy of intersection sight distances and adequacy of project parking were identified as potential impacts. Staff is recommending project modifications beyond the scope of the mitigation measures to address these impacts based on project merits and not merely CEQA issues. The project will be required to pay its pro-rata share of traffic impact fees to address cumulative traffic generation impacts.

Zoning Ordinance Conformance

Section 4.08.04 of the Tiburon Zoning Ordinance sets forth the following principles to be evaluated in the review of Precise Development Plan applications. A summary of this project’s conformance with these principles is as follows:

(a) Significant open space shall be preserved, through dedication or other means acceptable to the Town, consistent with policies of the Open Space and Conservation Element of the Tiburon General Plan.

The project would leave approximately two-thirds of the site in an open condition, including the oak trees, the drainage channel and riparian areas, and the ridgeline. The proposed precise plan does not specify the method that would be utilized to preserve this open space. Developments of this nature typically confer "open space easements" to the Town over portions of the privately owned lots located outside the building and landscape envelopes. Staff does not recommend fee dedication of land in instances such as this project, where the remaining open space is isolated from other dedicated open space areas, and has no public trails or connections. Staff has considered the possibility of a pedestrian easement from either Silverado Drive or Comstock Drive to the nose of Secondary Ridgeline #3 for purposes of a public viewpoint, but both options have obstacles that the property owner and Town may not be able to overcome.

(b) Preservation of natural features of the land shall be achieved to the maximum extent feasible through minimization of grading and sensitive site design. Features worthy of preservation include ridgelines, prominent knolls, desirable native vegetation, trees, significant rock outcroppings, water courses, and riparian corridors.

The applicant has made significant efforts to design the proposed project to preserve the natural features of the site. The building envelopes have been placed on the lower and flatter portions of the property to avoid development of the more pronounced hillside and ridgeline portion of the site. Significant vegetation and riparian areas have been avoided.

(c) Slopes created by grading should not exceed 30 percent. Final contours and slopes should reflect natural land features.

Most of the earthmoving activities would involve the removal of landslide and debris flow material, and recompaction of these same areas into stable slopes. Cutting and filling for the project roadway and individual homes will also occur. Final graded slopes shall not exceed 30% and shall resemble natural terrain.

(d) Every reasonable effort shall be made to preserve view corridors, mature trees, rare plants, significant native flora and fauna, areas of historical significance, access corridors, and habitats of endangered species.

Story poles have been erected by the applicant at the approximate locations of the homes to be built on each of the four proposed lots. A story pole and staking plan is attached as Attachment D. As the poles were erected too late for a field visit prior to this report, Staff will reserve the evaluation of visual impacts at this time and provide an update at the public hearing.

(e) Location of development well below ridgelines shall be achieved, in accordance with General Plan and other policies.

Building envelopes on Lots 2 and 3 approach the lowermost reaches of Secondary Ridgeline #3 as identified in Resolution No. 2859. Staff is recommending an increased setback on Lot 3 to further insulate the secondary ridgeline from encroachments.

(f) Prominence of development and construction should be minimized by appropriate location of grading and placing of buildings so that they are screened by wooded areas, rock outcroppings and depressions in topography or other features.

The property’s open hillside nature limits the ability to "hide" proposed homes using site features. Prominent trees on the site are located at the upper reaches that are inappropriate for development. Depressions in topography on this site are typically drainageways that should be avoided. On properties such as this, appropriate design of homes (in terms of height, size, mass, bulk, color, shape, architecture and materials) is the best tool to achieve compatible construction that blends to the extent possible with the surroundings. "Show-me" homes and "monster" homes should be avoided on such sites.

(g) Due consideration shall be given to avoidance of areas posing geological hazards.

Because of the potential to affect off-site improvements and property, the geologically unstable areas of this site are required to be repaired under the Town’s policies regardless of the location of development on the site. By fortunate coincidence, much of the area to be disturbed by proposed site improvements (roadway and homes) overlaps areas that will have been previously modified or excavated and reconstructed as part of required slide repair and stabilization procedures.

(h) Minimization of significant adverse impacts, as detailed in the Environmental Impact Report, if one is required.

A Draft Mitigated Negative Declaration and expanded Initial Study concluded that all potential adverse impacts to the physical environment, as defined by CEQA, are reduced to less than significant levels by mitigation measures incorporated into the project. Please refer to the Initial Study for details.

(i) Roads shall be designed for minimum slopes, grading, cut-backs and fill. Narrowing of roadways may be allowed to reduce grading, retaining walls, and other scarring of the land.

The single access road serving the proposed project winds initially to the east before turning westward. The roadway would have a width of 20 feet, the narrowest width recommended by the Fire District. The alignment of the road is remarkably similar to that of nearby Trestle Glen Terrace, although located on steeper terrain. The slope of the proposed road does not appear to exceed 16% at any point and thus would meet applicable standards for fire, emergency, utility and service trucks such as refuse collection vehicles. In comparison, Taylor Road, a public street off Paradise Drive, maintains a 25% slope over a considerable distance.

(j) Proposed arrangement of residential units and design of circulation system shall provide harmonious transition from and be compatible with, neighboring development and open space. Monotony in design shall be avoided.

The project is designed to be independent of surrounding neighborhoods in terms of access and respects preservation of open space as about two-thirds of the site will remain permanently open.

(k) Adequate consideration shall be given to the need for privacy and with minimum visual and aural intrusion into indoor and outdoor living areas from other living areas.

Staff has preliminarily concluded that the location of the proposed building envelopes would create adequate separation between the future houses and nearby existing homes, insuring the privacy of neighboring residents. Privacy issues can be addressed in much greater detail at the site plan and architectural review permit level.

(l) Improvements shall be placed so as to minimize intrusion of noise on nearby areas.

The noise study prepared for the project by Lumina Technologies determined that the locations of the homes would not result in any long-term significant noise impacts on the surrounding areas.

(m) Landscaping shall be designed so as to result in the least possible disturbance of natural and/or open areas and shall be compatible with the natural setting. Consideration shall be given to fire protection, water conservation, protection of views and trail areas, and buffering of noise.

Landscaping would be limited to the building envelope and landscape envelope areas surrounding the homes, all of which are in the least environmentally sensitive portions of the site.

(n) Utilities shall be underground and street lights, if needed, shall be of low intensity and low in profile.

Streetlights (if any) for this project would be the minimum to achieve public safety. Low level roadway downlighting would be more appropriate, and would be reviewed by the Town during its review of the subdivision improvement drawings and by the Design Review Board during its review of any homes eventually proposed on the site.

(o) Materials and colors used in improvements shall blend into the natural environment to the extent reasonably possible.

This is a standard condition of approval for planned developments in Tiburon. Medium-to-dark earth tone colors are generally preferred by Town Staff as blending better with the surrounding environment. A "design theme", such as Craftsman Style, has been required by the Town on occasion when compatibility concerns are pronounced.

(p) Consistency with other goals and policies of the General Plan Elements shall be demonstrated.

See the General Plan discussion below.

General Plan Consistency

The following section addresses the policies of the Tiburon General Plan that relate to this proposed project:

LU-B To ensure that all land uses, by type, amount, design, and arrangement serve to protect and enhance the low-density residential and village character and image of the community.

The proposed density of less that one unit per three acres is quite low, roughly one-twelfth that of

Belveron Gardens. The arrangement of units in a semi-clustered manner that respects the

environmental limitations of the site while preserving its most visually prominent portions will

enhance the image of the community.

LU-12 In Planned Residential Districts, new development should be located on the least environmentally sensitive and least hazardous portions of vacant land wherever feasible to promote sound land development and planning practices. Special emphasis shall be placed on keeping ridgelines open and unobstructed to the maximum extent feasible.

The biological study prepared for this project found that special status species are absent. Development is lightly clustered in the lower portion of the site away from environmentally sensitive resources on this property. Project construction would avoid oak woodlands on the upper reaches of the property and a riparian drainage on the northeastern edge of the site. An open space easement would protect these areas. Secondary Ridgeline #3, as identified in Town Council Resolution No. 2859, crosses a portion of the site, dropping down from Redding Court above. The most visually prominent portions of this secondary ridgeline would be preserved as open space. The lowermost (least visible) reaches of the secondary ridgeline are located in between the building envelopes for Lots 2 and 3. A minor enhancement to protection of the secondary ridgeline could be achieved by increasing the Lot 2 building envelope setback from the ridgeline to 30 feet from the current 12 feet, for a total setback of 42 feet.

OSC-B To provide a flexible guide for landowners to submit proposals for development which will preserve as much open space as possible and result in protection or enhancement to the maximum extent feasible of shorelines, open water, wetlands, significant ridgelines, riparian corridors, steep slopes, rock outcroppings, rare and endangered plant and animal habitat areas, other significant vegetation, and areas of visual importance.

The project would retain the site’s steep slopes and riparian corridors in private open space and

protected by an open space easement. Significant trees and biological area are likewise avoided.

The secondary ridgeline is largely avoided.

OSC-2 Growth. While accommodation of growth is an accepted reality, it should be so directed as to preserve and enhance views, ridgelines, significant vegetation, habitats and environmentally sensitive areas to the maximum extent feasible. New development shall be in harmony with adjacent neighborhoods and surrounding open space areas.

The proposed project would maintain approximately two-thirds of the property as open space outside of building and landscape envelopes. The envelopes would avoid the sensitive vegetation on the upper portion of the property and preserve the mature trees on the site. The design of the project would not excessively impact the views of neighboring residences.

OSC-3 Outward Views. Property owners cherish their views. New structures and associated landscaping should be situated or kept low to avoid interference with existing outlooks.

The project building envelopes are designed such that view blockage internal to the subdivision

should not result.

OSC-4 View Corridors. Principal inboard and outboard vistas should be defined and development should be located to protect such vistas to the maximum extent feasible.

The project is not anticipated to result in primary view blockage from any existing residence. A visual simulation is included in the Initial Study document as Figure 4. The visual backdrop of the ridgeline and middle and upper reaches of the property remains intact as open space.

OSC-11 Grading and Tree Removal. The Town shall encourage location of structures in a manner that minimizes tree removal and grading. Specifically, grading shall be kept to a minimum and every effort made to retain the natural features of the land including ridges, rolling land forms, knolls, vegetation, trees, rock outcroppings, and water courses. Where grading is required to stabilize areas of geologic instability, the graded area shall be returned to a natural landform. Excessive grading to stabilize soil is not in the best interest of the Town and is inconsistent with the Town=s desire to retain natural landforms. Therefore, excessive grading is to be avoided to the maximum extent feasible.

The project would avoid removal of all significant trees on the site. Due to the topography of the site, roadway grading will be substantial. However, the proposed roadway area coincides with landslide and debris flow areas that, pursuant to Town policies, would require correction in any event prior to development of the property.

OSC-15 Site Coverage. To the maximum extent feasible, a goal of 50% of large undeveloped parcels should be considered for retention in permanent open space outside of any parcel or lot which has development potential. Such open space shall be contiguous and link up with adjacent open space whenever practicable. Where a more desirable site plan would result, consideration may be given to larger individual lots. In the latter case, to the maximum extent feasible, 50% of the large undeveloped parcel should be retained in open space and the portions of open space within a parcel or lot with development potential should be restricted from development by open space easement or other appropriate means. This policy shall not require or preclude clustering and protection of open space views shall be accomplished through appropriate building and site coverage restrictions.

See discussion under Section 4.08.04 (a) above. Over two-thirds of the property would remain as open space. The project is lightly clustered but will retain a spacious appearance.

ISSUES

The subject property is characterized by numerous physical and environmental constraints that largely drive the site design and the location of proposed development. Staff believes that the project, on balance, furthers the goals, objectives and policies of the Tiburon General Plan and Tiburon Zoning Ordinance. While supportive of the proposed project design overall, Staff is of the opinion that certain modifications to the project would serve to increase conformity with the Town’s regulatory documents and achieve a superior project from that standpoint. These modifications are discussed below.

Project Access

Vehicular access to the project would be from a single private roadway off Trestle Glen Boulevard, centrally located along the frontage to be as far as possible from Juno Road (approximately 500 feet) and Mercury Avenue (approximately 470 feet) intersections with Trestle Glen Boulevard. These two Belveron Gardens Subdivision roadways enter Trestle Glen Boulevard with rather poor sight distance, especially Juno Road. The proposed private roadway location offers the greatest sight distance from both directions that could be provided along the subject property’s extensive frontage. Although the sight distances both east and west from the proposed new intersection technically meet minimum standards, this plan should strive to provide the best sight lines achievable.

Staff recommends that, in addition to Mitigation Measure Traffic-1 as set forth in the Initial Study, a condition be added that additional measures, including possible shaving back of the hill slopes above Trestle Glen Boulevard be required to maximize sight lines. If necessary, a flared project entry or deceleration area shall be constructed by the applicant subject to the recommendations of the Town Engineer.

The only other likely vehicular access point onto the property at this time would be from an extension of Silverado Drive, which could conceivably access the upper reaches of the site near the secondary ridgeline. Such an access would result in reduced conformance with the Town’s goals and policies, and was rejected early in the review process as discussed above.

Hammerhead versus cul-de-sac

The proposed private roadway ends in a hammerhead turnaround. The Tiburon Fire Protection District has indicated that the turnaround does not meet minimum standards required by the District. In any event, Staff believes that sound design principles and good planning demand a cul-de-sac at the end of this private roadway. The Fire Marshal has also indicated his strong preference for a cul-de-sac. While this may result in slightly more grading and slightly higher retaining walls, it should be noted that the home on Lot 1 would visually block most of the cul-de-sac from public view. The hammerhead turnarounds at the end of Reed Ranch Road and Blackfield Drive in the Ring Mountain Subdivision, and at the end of Avenida Miraflores, are fine examples of why cul-de-sacs are preferable to hammerhead turnarounds. Comparable cul-de-sacs can be found on Turtle Rock Court and on Trestle Glen Terrace.

Staff recommends that a cul-de-sac be required in place of the proposed hammerhead turnaround.

Retaining wall design and screening

Due to the steepness of the site, retaining walls will be required to support the proposed roadway. These walls could reach up to 11 feet from finished grade in places. While substantial portions of these retaining walls would be blocked from public view by a future home on Lot 1, it will be necessary for aesthetic purposes to require a high quality of design and appearance for these walls. In addition to facing, texturing, or coloring, or a combination thereof, for the walls, berming and landscaping should be required to minimize any remaining visual impacts.

Staff recommends that the Design Review Board approve all retaining walls associated with the project improvements prior to approval of the Subdivision Improvement Drawings by the Town. Specific direction shall be provided to the Board involving use of the above-described methods to reduce visual impacts.

Building Envelopes

As noted above, story poles have not been erected as of the writing of this report. Staff therefore reserves final comments until such time as a field inspection of the story poles can be made.

Preliminarily, Staff believes that the building and landscaping envelopes are properly placed on the site in general. However, the building envelope for Lot 3 is overly large and impinges too closely on the lowermost portion of Secondary Ridgeline No. 3. The building envelope should be scaled back 30 additional feet from the ridgeline, for a total setback of 42 feet, to further reduce impacts on this ridgeline. This scaling back will also assist with the creation of the cul-de-sac in that location. This envelope should not extend so far upslope and its upper portion should be scaled back to approximately the 130-foot contour line. Staff also believes that the building envelope for Lot 1 should be scaled back at its lower end to follow the 60-foot contour line. This would provide a minimum setback of 65 feet from the pavement of Trestle Glen Boulevard to the building envelope.

Staff recommends that the above-described envelope modifications be required.

Secondary Envelopes

Three very small secondary envelopes of dimensions 15’ X 20’ are proposed, one each for Lots 2, 3, and 4. These envelopes are intended for gazebos or other minor structures. Staff strongly believes that no envelopes should be placed within the open space area or upslope from the proposed V-ditch that defines the uppermost reaches of the landscape envelope.

Staff recommends that the secondary envelopes for Lots 2 and 3 should be moved within the landscape envelope on each lot or should be deleted.

House Sizes

Proposed house sizes are from 5,500 square feet to 7,500 square feet. Staff has indicated to the applicant that the upper limit of this range is larger than typically approved by the Town of Tiburon in new Precise Development Plans.

Staff recommends a maximum house size of 5,500 square feet, plus up to 750 square feet of garage, for each lot.

Parking

Due to the lack of on-street parking in the vicinity, each lot will be required to provide at least six (6) off-street parking spaces. To accommodate special events, the project CC&Rs will require valet parking or off-site parking with shuttle service.

Staff recommends that provision of at least four on-street parking spaces be seriously explored, either in the form of parking bays along the project roadway or in the vicinity of the cul-de-sac, or both.

Recreational Easements held by adjacent Trestle Glen Terrace properties

Three existing developed residential properties on Trestle Glen Terrace hold recreational back yard easements over adjacent portions of the subject property. These easements allow landscaping, decking, hot tubs, fences and improvements of a similar nature. As shown on the site plan, fencing already encroaches into portions of these easements and probably predates creation of the easements in 1996. The permit status of the existing fences must be researched by Town Staff, but it appears unlikely (though not impossible) that any permits were validly issued for the fences. This is because, per the Tiburon Zoning Ordinance, no improvements could be lawfully constructed on the Lower Trestle Glen property unless authorized by an approved Precise Development Plan. Nevertheless, the easements do constitute a form of "property right" for the Trestle Glen Terrace owners, and must be addressed in this Precise Development Plan.

Staff recommends that this Precise Development Plan set forth guidelines for the location and extent of future proposed improvements within these easement areas. The guidelines shall direct the Design Review Board in its review of any future applications for improvements in the easement areas. Preliminarily, the guidelines should encourage improvements to be in close proximity to the property line and to not be highly visible or disruptive of the hillside above.

Future Bicycle Lane on Trestle Glen Boulevard.

General Plan Circulation Element policy C-34 states that "a future bike lane may be considered along Trestle Glen Boulevard". In order to accommodate this future possibility, the Town will require a ten-foot wide roadway dedication along the entire frontage of the property. According to the Town Engineer, a bike lane project would need to be thoroughly investigated before determining which side of the street it might best be located. It is premature at this time to require any actual installation of improvements along the frontage of this property. If the Planning Commission considers a thorough investigation of a future bicycle lane to be a high priority, it should so recommend to the Town Council.

Agency/Department Comments

Letters have been received from the Town Engineer, Tiburon Fire Protection District, Richardson Bay Sanitary District, Marin Municipal Water District, and PG&E. These letters are attached as Exhibits 5 through 10. The comments indicate that the project design is feasible in terms of service capacity and provision. The comments are reflected in the Initial Study document.

Miscellaneous file letters regarding this site or its vicinity are attached as Exhibits 11 through 14.

FUTURE ACTIONS REQUIRED

The Planning Commission’s approval of this project would be in the form of a recommendation to the Town Council for project approval. The Town Council would then hold a separate public hearing to consider the project and the environmental determination.

Should the Commission vote to deny the project, the denial would be final unless appealed to the Town Council.

If the Precise Development Plan is approved by the Town Council, subsequent Town permits would include a Tentative Subdivision Map, Parcel Map, Subdivision Improvement Drawings, Site Plan and Architectural Review approval for each lot, and Building Permits for each residence.

This hearing will provide the best opportunity to hear from various technical experts who will be present at the meeting, including traffic, soils, and environmental consultants.

Staff recommends that the Planning Commission hold a public hearing on this item. Due to the tardiness of erecting the story poles, Staff recommends that the Commission continue the item to the October 11, 2000 meeting.

Staff requests preliminary feedback from the Planning Commission regarding the project and especially the "Issues" section in this Staff Report.

Staff will prepare a draft resolution for consideration by the Planning Commission at the meeting of October 11, 2000.

The adjacent Tiburon Court project is also scheduled for discussion on October 11^th. A drawing showing both projects together will be on display at both meetings.

1. Application Form received 12/30/99.
2. Letter from Frank Mullberg, 66 Hacienda Drive, dated 9/14/2000.
3. Letter from Randy Greenberg, 45 Norman Way, dated 9/20/2000.
4. Adopted Town policies regarding landslide repair, revised May 4, 2000.
5. Comments from Town Engineer dated 5/22/2000.
6. Comments from Tiburon Fire Protection District dated 4/12/2000.
7. Comments from Richardson Bay Sanitary District dated 3/1/2000.
8. Comments from Marin Municipal Water District dated 4/18/2000.
9. Comments from PG&E dated 4/11/2000.
10. Acknowledgement of Receipt from State Office of Planning & Research dated 9/6/2000.
11. Letter from Sharon Callahan, 31 Juno Road, received 3/3/97.
12. Letter from Sharon Callahan, 31 Juno Road dated 8/12/97.
13. Letter from Randy Greenberg, 45 Norman day, dated 6/21/99.
14. Letter from Dr. Michael Lagios, 11 Benton Court, dated 4/20/2000.

1. Full size drawings (6 sheets) prepared by Meridian Surveying dated March 15, 2000.
2. Reduced scale (11" X 17") drawings of the above (for field use).
3. Additional copy of Initial Study & Draft Mitigated Negative Declaration.
4. Story Pole and Building Envelope Staking Plan (11" X 17") for field use.

 

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