residential development may occur on unsubdivided lands in the San Juan Canyon area designated on the General Plan Diagram as Open Space. Consistent with the designation, any development in these areas must be clustered preserving most of the land in open space. Development should occur under planned development provisions of the Zoning Ordinance with density and location of housing units based on thorough evaluation of slope, slope stability, drainage, erosion potential, vegetative cover, adjacent land uses and visual impacts. Safe and adequate provision of access and public services must be assured prior to development approval."
Suggested amendment: delete.
Discussion: This descriptive section in the existing General Plan is not needed and would be superseded upon adoption of an area plan for the San Juan area.
Unsubdivided parcels in the San Juan Canyon area are designated as open space. In general, these areas are without adequate street access and public services. Most of the land is over 30 percent slope and some is geologically unstable. The open spaces are important elements in the natural drainage for the 796
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'
entire San Juan Canyon area. In addition to landslides and erosion hazards, wildfires are a potential hazard in this area.
The plan allows for clustered residential development in these open spaces. Development should be designed to retain a majority of the land in its natural state. In particular, unstable slopes over 30 percent, natural drainage ways, stands of trees, and visually prominent ridge tops should be retained in open space.
"Actions:
"a. When fiscally possible, evaluate the larger parcels in the San Juan Canyon area to identify the specific locations to be protected as open space.
"b. Explore means of protecting the most significant open space resources of the Canyon on a permanent basis."
Suggested amendment: Replace with - "San Juan Canyon. The San Juan Hills Area Plan contains provisions for protecting and enhancing private open space through density transfer,
clustering and open space easement policies."
Discussion: This suggested amendment would update the open space element and reference the Area Plan.
installed in all new residential developments except in areas where construction of sidewalks would be incompatible with existing development and/or require excessive grading or tree removal. In such cases, adequate roadway shoulders, or
alternative trails and pathways shall be provided to ensure the safety of pedestrians and bikers."
·Suggested amendment: Amend last sentence to read - "In such cases, adequate roadway shoulders, sidewalks limited in width or location, or alternative trails and pathways shall be provided I
to ensure the safety of pedestrians and bikers." (amended area ,is highlighted)
I :Discussion: The City Code provides for the reduction of sidewalk width and other exceptions related to topographic /constraints. This amendment would make the existing General ;Plan and City Code consistent and reflect the proposed standards 'in the Area Plan.
access to abutting property. They are designed to discourage 3 797
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through traffic and are an important element in community design providing a framework for building location. Additional minor streets will be needed in Belmont to provide access to new development, particularly in the Western Hills and East Belmont areas. Also, alignment and configuration of the system of minor streets in the San Juan area needs to be determined. An important aspect of the San Juan area circulation system will be the identification of through road connections, either open or restricted to emergency use, to insure secondary access in times of emergency.
Suggested amendment: Delete last two sentences.
Discussion: This description of streets in the San Juan area is superseded by the Area Plan.
Waltermire Street, F.mmett Street, Arbor Avenue, Lake Road, Molitor Road, Shoreway Road and portions of Notre Dame Avenue and Sixth Avenue, have been identified as substandard in width.
Many of these streets cannot be widened without severe
disruption to adjacent uses or unacceptable loss of parking capacity. Widening of all or portions of these streets should occur only when and if necessary for safe movement of traffic.
Decisions regarding the future of the unimproved roads in the San Juan area will be made following evaluation of physical conditions and possible development patterns in this area." Suggested amendment: Delete last sentence.
Discussion: This discussion of unimproved .roads is superseded by the Area Plan.
investigations by both registered soils engineers and
engineering geologists prior to issuing building permits for any new construction unless waived due to current existing
information and location. All such reports shall be
independently evaluated, on behalf of the City, for completeness and accuracy.
Suggested amendment: Amend the first sentence to read - "The City shall require investigations by both registered soils engineers and engineering geologists prior to issuing building permits for any new construction in areas of suspected geologic and soil instability unless waived due to existing, current information.
798
"
"San
I.
Discussion: The city does not now require both a soils and geologic report for all new construction. Both reports are only required in areas of suspected geologic and soil instability.
The proposed amendment (highlighted area above) would make the existing General Plan consistent with current City practice and with the proposed policies for development in the San Juan Hills Area Plan.
Page
Site
3-36, Table 15:
1982 Revised
General Plan
Designation
Existing Redevelopment Services
Zoning(ll Area Available
Juan Area low density R-lB
residential, A no DO
open space R-lE"
Suggested amendment: replace 1982 revised General Plan
designation and existing zoning information with - "refer to Area Plan."
Discussion: This amendment will eliminate obsolete general plan and zoning designations from the General Plan and refer readers to the Area Plan.
l:sjgpa.txt
s 799
800
RESOLUTION NO. 1987-�
RESOLUTION OF THE PLANNING COMMISSION OF THE CITY OF BELMONT
RECOMMENDING CERTIFICATION OF THE ADEQUACY OF THE
FINAL ENVIRONMENTAL IMPACT REPORT FOR THE PROPOSED
GENERAL PLAN AMENDMENT, INCLUDING THE ADDITION OF THE
SAN JUAN HILLS AREA PLAN AND TEXT CHANGES TO THE GENERAL PLAN
TO INSURE CONSISTENCY BETWEEN THE SAN JUAN HILLS AREA PLAN AND THE REST OF THE GENERAL PLAN (APPL. NO. 86-1079)
WHEREAS, a draft environmental impact report (EIR) was prepared, dated April 1987, for the amendment of the General Plan which would add the San Juan Hills Area Plan to the General Plan and revised the text of the General Plan to make the General Plan to insure consistency between the General Plan and the San Juan Hills Area Plan; and, WHEREAS, said draft EIR was circulated to all responsible agencies and was available for review by the public for a minimum of 45 days subject to publication; and,
WHEREAS, public hearings were held by the Belmont Planning Commission on May 5 and 19, 1987, at which times all interested parties were afforded an opportunity to be heard on the adequacy, completeness, and good faith effort at full disclosure of the environmental effects of the project and recommended mitigation measures; and,
WHEREAS, the final EIR was then developed consisting of the draft EIR, responses to comments received on the draft EIR and comments and final EIR was reviewed and acceptable to both the City of Belmont Planning staff and the Planning Commission; and,
801
WHEREAS, the public hearing was held on August 4, 1987 by the Belmont Planning Commission to allow all interested parties to be heard on the adequacy of the final EIR.
NOW, THEREFORE, BE IT RESOLVED that the Planning Commission of the City of Belmont hereby finds that the final EIR is complete and in good faith effort at full disclosure of the environmental effects of the project and recommended mitigation measures and recommends certification of the final EIR for the amendment of the General Plan to incorporate the San Juan Hills Area Plan, and text amendments to insure consistency between the General Plan and the San Juan Hills Area Plan. * * * * * * * * * * * * * * *
Passed and adopted at a regular meeting of the Belmont Planning Commission held on August 4, 1987 by the following vote:
AYES,
COMMISSIONERS:Rianda, Feierbach, Green, Lawhern, Bohl, Della-Santina NOES,
COMMISSIONERS:=N=on=e=------------------------
ABSENT,
COMMISSIONERS:�c=l-l=i=n-sc...----------------------
ABSTAIN,
COMMISSIONERS:=N.,..n=e=----------------------------
Planning Commission Secretary
45/rsjsr
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APRIL 1987
PREPARED FOR
CITY OF BELMONT
PREPARED BY
LARRY SEEMAN ASSOCIATES, INC.
157 PARK PLACE
POINT RICHMOND, CA 94801
(415) 236-6810
LSA #BEL601
803
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TABLE OF CONTENTS
Page
INTRODUCTION 1
SUMMARY 4
PROJECT DESCRIPTION 15
Location 15
Project Objectives 15
Technical Project Description 20
Conformance with Other Plans and Policies 32
Relationship to Other Planned Projects 41
Jurisdictional and Permit-Granting Agencies 42
ENVIRONMENTAL SETTING, POTENTIAL IMPACTS AND MITIGATION MEASURES 43 Land Use and Population 43
Geology and Soils 48
Hydrology and Drainage 57
Vegetation and Wildlife 62
Visual Quality 71
Traffic and Circulation 81
Climate and Air Quality 97
Noise 111
Public Services and Utilities 118
Energy Conservation 127
TOPICAL ISSUES ANO IMPACT OVERVIEW 131
Effects Found Not to be Significant 131
Potentially Significant Effects Subject to Mitigation 131 Unavoidable Significant Adverse Impacts 133
Irreversible Environmental Changes . 134
Relationship Between Local Short-Term Uses of the
Environment and the Maintenance and Enhancement of
long-Term Pr6ductivity 135
Cumulative Impacts 135
Growth-Inducing Impacts 137
Alternatives 137
PERSONS PARTICIPATING IN THE PREPARATION OF THIS STUDY 142 PERSONS AND AGENCIES CONTACTED DURING REPORT PREPARATION 143 REFERENCES 144
805
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APPENDICES
Appendix A - Initial Study
Appendix B - Proposed Floor Area Ratios (Slope Intensity Table) and Alternative Slope Density Formulas
Appendix C - Species Lists for San Juan Hills Planning Area Appendix D - Traffic Data
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iii
LIST OF FIGURES
Figures
I. Regional Location
2. Planning Area Boundaries
3. Aerial Photograph of San Juan Hills Area
4. Existing Vacant Land and Unimproved Roads
5. San Juan Hills Subareas
6. Land Use Policy Map
7. Location of Future Development
8. Existing General Plan Land Use Map
9. Geologic Features
10. Geologic Hazard Policy Map
11. Laurel Creek Watershed
12. Storm Drainage Improvements
13. Vegetation Map
14. Project Area Photograph: Upper Laurel Creek Canyon From Marsten Avenue
15. Project Area Photograph: View from Ralston Avenue Vista Point
16. Project Area Photograph: New Residential Development on Hillsides
17. Project Area Photograph: Horse Ranch Property
18. Project Area Photograph: Baptist Church Property
19. Local Road Network
20. Existing and Future Traffic Volumes
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Page
16 17
18 19
22 27
33 39
49 51
58 60
63 72
73 75
77 78
82 85
807
I
808
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LIST OF TABLES
Tables
I. Current Vacant Lots and Maximum Buildout Potential Under the San Juan Hills Area Plan 23
2. Slope Density Formula for Hillside Residential and Open Space Areas 29
3. Geologic Hazard Criteria for Development 54
4. Intersection Service Levels 87
5. Roadway Impacts Due to Planning Area Buildout Traffic 90
6. Cumulative Project Trip Generation 92
7. Traffic Impact on Residential Environment 94
8. Ambient Air Quality Standards 100
9. Belmont Ambient Air Quality Monitoring Summary 101
10. Vehicular Source Air Emissions Due to San Juan Hills Planning Area Buildout 104
11. Mobile Source Emissions Comparisons 105
12. Vehicular Emissions Microscale Impact Assessment 107
13. Development-Related Total Emissions 109
14. Existing Noise Contours Adjacent to Ralston Avenue 113
15. Projected Noise Contours Adjacent to Ralston Avenue 116
16. Status of Unimproved Roads and Paper Streets in the San Juan Hills Planning Area 122
17. Number of Units Permitted by Alternative Slope Density Formulas 139
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INTRODUCTION
This Environmental Impact Report (EIR) addresses the effects of the proposed San Juan Hills Area Plan which is referred to as the "project". The San Juan Hills area is located in the northwest portion of the City of Belmont. The 1,000-acre San Juan Hills planning area is bounded by Ralston Avenue on the south, Cipriani Boulevard on the east, the City of San Mateo on the north and the County of San Mateo on the west.
If adopted, the Area Plan would amend arid supplement the City of Belmont General Plan with a comprehensive set of policies to guide development in the San Juan Hi 11 s area. In accordance with Ca 1 i forni a Government Code Sections 65100 and 65301, the Area Plan is a means to develop focused policies in a City's General Plan which address the unique problems and assets of the planning area. When adopted, the Area Plan would become part of the Belmont Genera 1 Pl an and, therefore, it must be consistent with the over a 11 goa 1 s, objectives and policies of the General Plan. Implementation of the Area Plan would be achieved through the development of several ordinances and regulations including a slope density ordinance, lot merger ordinance, density transfer regulations, geologic hazards regulations and other minor amendments to grading ordinances, etc.
The Area Plan was developed by a special committee, the San Juan Committee, in conjunction with City planning staff and consultants. Public input was solicited from community members and affected agencies during a 11 phases of Plan development.
The San Juan Hills Area Plan is based on an extensive analysis of the 1 and use and resource constraints of the area. The proposed Area Pl an sets forth policies regarding geologic hazards, natural resources, land use and site development standards, and infrastructure in the San Juan Hills area.
Implementation of the Area Plan would lower the potential buildout of the San Juan Hi 11 s and would result in a different development pattern than would occur under the General Plan.
This EIR addresses the environmental effects of future development in the San Juan Hills under the proposed Area Plan. Potential impacts are evaluated in terms of the change in land use designations and policies from the existing General Plan. Impacts are also analyzed according to the cumulative impacts resulting from deve 1 opment permitted under the proposed Area Pl an. The potential impacts of the various implementing ordinances and actions necessary to implement the Area Plan have also been assessed in this EIR. As long as the implementing actions do not significantly differ from those discussed in 811
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this EIR, no further environmental review for the Area Plan or implementing actions will be necessary.
The City of Belmont Planning Department prepared an Initial Study for the project in accordance with CEQA guidelines. The Initial Study is included as Appendix A and focuses the analysis on the following areas of environmental concern:
1. Land use impacts, particularly changes in development locations, changes in permitted densities, and any potent i a 1 1 oss of open space;
2. Geologic hazards and grading impacts;
3. Hydrologic impacts, including drainage improvements and additional -I runoff;
4. Traffic and circulation system impacts, including effects of road improvements, rerouting of currently unbuilt rights-of-way and need for emergency access;
5. Air quality impacts;
6. Increased noise levels due to traffic and construction;
7. Effects on vegetation and wildlife habitat, especially in Laurel Creek Canyon;
8. Visual impacts of proposed development; and
9. Effects of development on urban services, including fire, police, road maintenance, and the provision of water, sewer and energy services; and
10. Cumulative impacts from development in the area.
In addition to the proposed Area Plan, three alternative development scenarios are evaluated in this EIR, including the No Project Alternative required by the California Environmental Quality Act {CEQA), a More Restrictive Alternative (i.e., permitting less development), and a Less Restrictive Alternative (i.e., permitting more development).
The primary purpose of an EIR is to serve as an objective, informational document to be used by lead and responsible agencies in their consideration of 812
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a project. For this project, the City of Belmont is the lead agency and will consider approval of the San Juan Hills Area Plan. Concerns and issues raised during the public review period for this Draft EIR will be addressed in a Final EIR prior to consideration of the project by the Belmont City Council. 813
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SUMMARY
The proposed San Juan Hills Area Plan would amend and supplement policies of the City of Belmont General Plan. The Area Plan includes detailed policies which address the unique environmental conditions of the San Juan Hills and would guide future development in the planning area. Overall, the Area Plan would permit less development in the San Juan Hills than could occur under the existing Genera 1 Pl an. Consequent 1 y, the env i ronmenta 1 effects of p 1 ann i ng area buildout under the Area Plan would be less severe than under the General Pl an.
This EIR evaluates the changes in policies and implementing ordinances that would occur with adoption of the Area Plan and assesses the impacts of buildout under the Area Plan in comparison with existing conditions in the planning area. The following discussion presents a summary of the adverse impacts associated with development under the proposed Area Plan and identifies possible mitigation measures. The extent of impact reduction to insignificant levels for each of the possible mitigation measures is also identified.
Land Use. Development under the San Juan Hills Area Plan would result in a lesser level of impact than the General Plan as the amount and location of development would be premised on environmental constraints. The following land use impacts would occur:
1. The Area Pl an would change the 1 and use des i gnat i ans specified in the General Plan and would result in a redistribution of development potential. The Area Plan would shift development into slightly lower densities on the steeper slopes and higher densities on the shallower slopes.
2. The total number of units permitted at buildout under the Area Plan would be reduced relative to the number of units permitted in the General Plan.
3. Implementation of Floor Area Ratios (FAR) as instituted in the Area Plan would strictly limit development on very small lots and lots with moderate geologic hazards. Lots that are in critical geologic hazard areas are not buildable under the Plan, but the FARs would provide some density transfer capacity for such lots.
4. If the Area Plan is fully implemented, lot mergers, resubdivision, and density transfers in the subdivided hillside areas would result in development of clustered units at the end of cul-de-sacs. 815
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The following measures are recommended to offset potential adverse effects and would reduce potential land use impacts to a level of insignificance:
1. The City should take an active role in encouraging participation in the lot merger, resubdivision and density transfer programs of the Pl an.
2. Where development at the ends of cul-de-sacs would result in densities of development which are significantly greater than nearby uses (i.e., townhouses, attached units, etc.), buildings should be designed to promote visual blending. The siting of buildings and landscaping should be sensitive to existing view corridors from surrounding residential areas.
Geology and Soils. Area Plan policies were formulated based on a detailed assessment of geologic conditions in the San Juan Hills (William Cotton and Associates report). Development under the Area Plan would be less than under the General Plan and would be restricted to areas where hazardous geologic conditions can be mitigated. Detailed geologic investigations would be required to prevent the siting of development on or immediately downslope of potentially unstable slopes. Potential landslide risks resulting from alteration of drainage patterns, undercutting the bases of slopes, or loading the tops of slopes would be minimized through implementation of the geologic hazards ordinance. The project would directly or indirectly result in the following impacts:
1. According to the Geologic Hazard Policy Map, most of the development permitted under the Area Plan would occur on or immediately downslope of potentially unstable slopes. If slope stability and drainage hazards are not properly mitigated, considerable damage could occur. Mitigation of potential geologic hazards could also result in impacts associated with vegetation removal, increased erosion and creation of unnatural slopes. Policies in the Area Plan are intended to minimize potential hazards due to development and also to minimize impacts resulting from geotechnical mitigations.
2. Future development under the proposed Area Plan would be subject to seismic groundshaking and related ground failures in the event of an earthquake emanating from the San Andreas fault.
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The following measures are recommended to offset potential adverse effects and would reduce potential adverse geologic impacts resulting from development under the Area Plan to a level of insignificance:
1. The recommended land use policies of the William Cotton and Associates report (April 1985) should be included in the implementing ordinances for the Area Plan.
2. The implementing ordinance for the geologic hazards policies of the Area Pl an should specify that the scope of soils engineering and engineering geologic investigations follow the guidelines recommended in the Cot ton and Associates report as we 11 as any additional standards and guidelines developed by the City. Slope stability studies should be based on quantitative analyses and should address expected seismic conditions.
3. The geologic hazards ordinance should require that soils engineers and engineering geologists submit project completion reports stating that plans, grading operations, and foundation excavations are in accordance with their original recommendations.
4. The implementing ordinance for the Area Plan should include a grading prohibition during the rainy season between October 15- April 15.
Hydrology. Since development under the Area Plan would result in a bui 1 dout of fewer resident i a 1 uni ts in the San Juan Hil 1 s than permitted by the existing General Plan, potential hydrologic impacts would be reduced. In addition, the Area Plan includes storm drainage policies which regulate the siting and design of development to ensure that stormwater does not damage structures and is not directed so as to cause downhill flooding or slope stability problems. Nevertheless, increased impervious surfaces and alterations of surface and subsurface· drainage patterns would directly or indirectly result in the following impacts:
1. Future development under the proposed Area Plan would increase the amount of impervious surface in the watershed of Laurel Creek by approximately 20 acres. This would increase peak flows at the mouth of East Laurel Creek by approximately 25 percent for the IO-year storm event and 15 to 20 percent for the 25-year event. If not properly mitigated, these greater 1 eve 1 s of runoff could increase bank erosion along. East Laurel Creek and Laurel Creek. 817
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2. Increased surface runoff directed onto slopes in the planning area could cause slope erosion and could trigger landslides.
The following measures are recommended for inclusion in the implementing ordinances to offset potential adverse hydrologic effects of future development under the Area Pl an and would reduce impacts to a 1 eve l of insignificance:
I. The storm drainage improvements recommended by the Storm Drainage Task Force should be adopted and implemented.
2. A storm drainage investigation should be conducted which addresses not only localized drainage in the San Juan Hills area, but also downstream effects. This study should evaluate potential increased peak flows in laurel Creek and the potential for creekbank erosion and deposition downstream. The possibility of developing a series of check dams to capture silt and check erosion and/or developing retention basins to decrease peak flows should be addressed.
3. Drainage from roadways and resident i a 1 deve 1 opment under the Area Plan should not be directed onto unprotected slopes or creek banks.
Where runoff must flow from impervious surfaces onto natural ground, proper energy dissipation structures should be provided.
4. If the western canyon area (upper elevations of East Laurel Creek Canyon) is developed, drainage design would need to include downdrains similar to those proposed for San Juan Canyon.
5. The City should develop guidelines for minimum setbacks for structures from San Juan and East laurel Creeks. Creek setbacks should be a minimum distance of 2 1/2 : 1, horizontal to vertical, from the creekbed or as specified by the City Geologist and should allow a working area for maintenance.
Vegetation and Wildlife. Since fewer residential units would be built under the proposed Area Pl an than could be bu i 1 t under the Genera 1 Pl an, development under the Area Plan would result in less removal, disturbance, and degradation of vegetation and wildlife resource. Development under the Area Plan would directly of indirectly result in the following impacts:
1. Development under the Area Plan would result in the removal and/or alteration of native vegetation species and their respective habitat types.
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2. Full buildout on the upper elevations of the Laurel Creek Canyon subarea would result in the removal of substantial acreage of grasslands.
3. Full implementation of the proposed density transfer program would result in preservation of the sensitive riparian woodland vegetation in Laurel Creek Canyon.
4. Development under the Area Plan could adversely impact wildlife in the San Juan Hills by introducing additional domestic animals into the planning area.
The following measures are recommended for inclusion in the implementing ordinances for the Area Plan. They would offset potential adverse effects of development under the Area Plan and would partially mitigate potential adverse impacts:
1. The loss of annual grassland, chaparral, eucalyptus and mixed evergreen woodland on the receiver sites would be mitigated through the creation of permanent open space on the sender sites.
2. As required by the State Fish and Game Code, a 1601 or 1603 streambed alteration agreement must be negotiated prior to any development which would result in alteration of East Laurel Creek or its associated riparian vegetation.
3. Native plant species should be used for revegetation and landscaping purposes in areas where residential development occurs in order to provide habitat for and minimize impacts on suburban wildlife.
Native species valuable to wildlife and suitable for landscaping include such species as California black walnut {Juglans hindsii), coast silk tassel {Garrya elliptica), coffeeberry {Rhamnus californica) and ceanothus.
4. If vegetation is cleared, manual removal of undesirable vegetation, rather than herbicide treatment should be instituted.
5. To preserve wildlife habitat in East laurel Creek, dead and down debris should be maintained unless it poses the potential for fire or flood hazards.
6. Equipment operation should be avoided within the dripline of all trees to be preserved. Once equipment operation is completed, disturbed areas within driplines should be lightly spaded by hand to 819
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loosen surface soil. Leaf 1 i tter and understory vegetation, which would act as a buffer against compact ions, should be retained in areas of equipment operation.
7. Irrigation and sprinkler systems, as we 11 as drainage from residential rooflines, should be diverted to avoid dripline areas.
Visual Quality. Buildout under the Area Plan would result in different pattern of deve 1 opment than could occur under the General Pl an with fewer residential units located in different areas. Future development under the proposed Area Plan would directly or indirectly result in the following impacts:
1. Development under the Area Plan would reduce potential visual impacts re 1 at i ve to deve 1 opment under the Genera 1 Pl an by consolidating the spatial dispersement of development.
2. Future development would impair the visual quality of the San Juan Hills as viewed from certain areas, particularly of the three designated receiver sites in the Laure 1 Creek Canyon subarea. In general , the lower development densities permitted in these areas would partially offset visual impacts although potential visual incongruities due to the development of attached dwelling units could occur.
3. Development of residences and roadways would result in a more urban character in the area and would result in the removal of a substantial amount of natural vegetation and open space.
4. Imp 1 ementat ion of deve 1 opment standards inc 1 uded in the Area Pl an would ensure that future residential development is compatible in scale with nearby uses and that the visual impact of development on hillsides would be regulated.
5. The Area Plan would promote the preservation of the natural integrity of building sites.
The following measures are recommended to offset potential adverse visual effects and would reduce impacts to a level of insignificance:
1. Development on the Horse Ranch and the two parcels adjacent to the Baptist Church should be sited and designed to minimize visual imp acts. Design f ea tu res which promote vi sua 1 b 1 ending of structures into the landscape should be encouraged.
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2. The implementing ordinances of the Area Plan should require that revegetation efforts utilize native and drought-resistant plant species. Revegetation should be established in patterns which are harmonious with existing vegetation in the area.
3. Design review approval should be required for new single-family residences in the San Juan Hills area and a case-by-case determination should be conducted to ensure effective application of the visual standards.
Traffic and Ci rcul at ion. Al though . deve 1 opment under the proposed Area Plan would result in a lesser level of impacts on local roads and intersections than development permitted by the General Plan, buildout under the Area Plan would directly or indirectly result in the following impacts:
1. Development under the Area Plan would generate approximately 3,720 new daily two-way trips with about 250 new inbound and 125 new outbound p.m. peak hour trips.
2. Existing intersection p.m. peak hour level of service designations would remain the same at all analyzed locations after the addition of traffic generated by buildout under the Area Plan.
3. Existing traffic safety concerns in the planning area would increase with development under the Area Plan.
4. Cumulative development would generate an additional 3,245 two-way p. m. peak hour trips. Cumulative deve 1 opment would decrease the level of service at the Ralston Avenue/El Camino Real intersection, the Ralston Avenue/ Alameda De Las Pulgas intersection and the Ralston Avenue/Cipriani Boulevard intersection.
The following measures are recommended to offset potential adverse effects of development under the Area Pl an and would reduce environmental impacts to a level of insignificance:
1. New roadways through the San Juan Hills area are recommended to be built to the following minimum standards:
Width
20 ft.
28 ft.
36 ft.
On-Street Parking Allowed
No
One side only
Both sides
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2. Landscaping and brush within roadway rights-of-way should be trimmed back on intersection approaches where sight distances are limited.
3. A priority list should be developed to provide stop signs on lower volume approaches to internal intersections.
4. Right-turn deceleration lanes should be provided on the Ralston Avenue westbound approaches to Christi an Ori ve and centra 1 access Belmont Canyon Road.
5. Left-turn lanes should be provided or lengthened on the northbound Cipriani Boulevard approach to San Juan Boulevard and on the eastbound Ralston Avenue approaches to Cipriani Boulevard and Christian Drive.
6. On-street parking prohibitions along one side of the street are recommended for San Juan Boulevard from Monte Cresta Drive to Cipriani Boulevard and for the central access Belmont Canyon Road from Ralston to Hillcrest.
7. Al 1 new cul -de-sacs should have turn around areas 1 arge enough to accommodate fire and emergency vehicles.
8. Pathways or sidewalks should be constructed on at least one side of all new streets.
9. Green Court access to Christi an Ori ve should eventua 11 y be routed via Marsten Avenue.
10. Additional through and/or turn lanes would be needed at the Ralston Avenue/El Camino Real and Ralston Avenue/Alameda De Las Pulgas intersections to provide acceptable peak hour operation under existing, project and cumulative volumes. Separate signal phasing should be provided for left-turn movements from Alameda De Las Pulgas to Ralston Avenue.
Air Oua 1 i ty. Si nee bu i1 dout of the San Juan Hills under the proposed Area Pl an would be less than under the existing Genera 1 Pl an, the overa 11 level of air pollutant emissions would be less. Air pollutant emissions generated by development under the Area Plan would be insignificant at both a local and regional level. Development in the San Juan Hills planning area would directly or indirectly result in the following air quality impact:
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1. Construction activities would significantly increase the amount of dust generated at a localized level.
The fo 11 owing measures are recommended to offset potent i a 1 adverse air quality impacts related to development under the Area Plan. Implementation of these measures would reduce potential impacts to a level of insignificance:
1. Implement aggressive dust control measures as required by local ordinance and BAAQMD Rules and Regulations.
2. Perform major grading in spring when soil moisture is high to minimize fugitive dust generation.
3. Carry out major soil disturbance between 8 a.m. to 4 p.m. when winds are strongest to reduce the amount of dust settling out on nearby receptors and to obtain better area-wide dispersion of any fugitive dust.
4. Encourage alternate modes of transportation through sidewalks, bike paths and a covered transit stop along Ralston Avenue to reduce dependence on cars as the sole means of transportation.
Noise. Development under the Area Plan would generate incrementally less noise than development under the General Plan, but would directly or indirectly result in the following impact:
1. Construction activities would temporarily increase noise levels to a significant level.
The following measures are recommended to offset potential adverse effects and would reduce potential noise impacts to a level of insignificance:
1. Construction noise near noise-sensitive receptors should be limited to day-time hours between Monday and Friday from 7 a.m. to 5 p.m.
2. Any stationary on-site noise sources including, but not limited to, compressors, generators, or power saws should be equipped with hospital grade mufflers for engine driven sources, or should be surrounded by a temporary plywood enclosure as a noise baffle.
3. To reduce the small (0.5 to 1 dB) L10 increase from project and cumulative growth traffic, reduced vehicle speed should be promoted; and noisy vehicles should use the least noise sensitive routes. 823
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Public Services and Utilities. Development under the Area Plan would place less of a burden on public services and utilities than full buildout of the San Juan Hills under the existing General Plan, but would directly or indirectly result in the following impacts:
1. Future development in the planning area would not significantly increase requests for fire or police protection services. The clustered development pattern recommended in the Plan would improve emergency access.
2. The emergency access road proposed between Skymont and the rest of the San Juan Hills planning area would improve fire and police protection services.
3. Road development would be restricted to areas not exhibiting geologically hazardous conditions and hillside road development standards would be implemented to reduce grading and surface runoff.
4. Development under the Area Plan would have an insignificant impact on local schools.
5. Oeve l opment in the p 1 ann i ng area would require the extension of water and sewer mains into currently undeveloped areas.
The following measures are recommended to offset potential adverse impacts associated with development under the proposed San Juan Hills Area Plan. These measures would reduce potential environmental effects to a level of insignificance:
1. Residential development in Laurel Creek Canyon and other relatively unaccessible areas, should be encouraged to include indoor sprinkler systems and fire-retardant roofs.
2. The City should work with 1 andowners to facilitate imp 1 ementat ion of the density transfer program and the lot merger/resubdivision process through on-site studies and follow-up meetings.
3. To ensure adequate provision of emergency access to the Skymont area, the City should accept road dedication with maintenance responsibilities for Marsten Avenue.
4. As Marburger Avenue is improved to city standards, the severe geologic hazard should be removed to ensure safe year-round access. 824
14 lsa
5. In areas with no on-street parking, "no parking" signs should be installed and a rigorous enforcement program should be implemented.
6. Permeable paths in hillside areas should be designed to minimize maintenance requirements.
7. Roadway extensions in hillside areas should be required to be built prior to the issuance of building permits.
Energy Conservation. Since the Area Plan would allow development of fewer residential units than could be developed under the General Plan.
Development under the Area Plan would directly or indirectly result in the following impacts:
I. Development would result in initial energy consumption for site clearing and grading, construction of access roads and extension of utilities. Long-term energy impacts would result from heating and cooling of residential units, water heating, general gas and electrical household needs, and fuel for transportation.
2. Development would also result in a daily fuel consumption of 23,064 gallons of gasoline.
The following measures are recommended to offset potential adverse effects and would reduce energy conservation related impacts to a level of insignificance:
1. Development in the San Juan Hills planning area under the proposed Area Plan must comply with Title 24 Energy Conservation Standards of the California Administrative Code.
2. Residential structures should be aligned along an east-west axis or northwest-southwest axis to face as near to south or southwest as possible in order to gain maximum solar exposure.
3. Operation of construction equipment should be managed to avoid unnecessary fuel use. The amount of grading should be kept to a minimum.
4. Building designs should allow for natural ventilation during warm periods and take advantage of incident solar insulation during the winter.
825
826
15 - lsa
PROJECT DESCRIPTION
LOCATION
The San Juan Hi 11 s area is located in the northwestern portion of the City of Belmont on the eastern flanks of the Santa Cruz mountains. Belmont is in the center of the San Francisco Peninsula midway between San Francisco and Palo Alto (Figure l}. The San Juan Hills area is bounded by Ralston Avenue on the south, Cipriani Boulevard on the east, the City of San Mateo on the north and the County of San Mateo on the west. The 1 ,000-acre planning area comprises approximately 20 percent of the land area of the City and contains approximately 1,100 dwelling units.
Figure 2 depicts the planning area boundaries. As shown, major arterials serving the area include Ralston Avenue to the south and Alameda de Las Pulgas to the east. State Route 92 (J. Arthur Younger Freeway} is to the west of the planning area and provides access to Interstate 280 ( Jun i pero Serra Freeway} to the west and San Mateo, Foster City, and Hayward to the east. 1-280 provides access to San Jose to the south and San Francisco to the north.
Major features in the planning area vicinity include Sugarloaf Mountain and Laurelwood Park to the north, John S. Brode Memorial Open Space and Water Dog Lake Park to the south, and the College of Notre Dame to the east. Figure 3 shows an aerial photograph of the planning area and identifies major features and subareas in the planning area including the Skymont, Plateau, and Cipriani residential areas, the Horse Ranch property, Sugarloaf Mountain, Laurel Creek Canyon and San Juan Canyon.
PROJECT OBJECTIVES
The proposed project consists of an Area Plan and its implementing ordinances which provide specific policies to address the unique problems and assets of the San Juan Hills area (City of Belmont, 1986). The Area Plan has been developed in accordance with California Government Code Sections 65100 and 65301, and if adopted would amend and supp 1 ement the City of Be 1 mont General Plan. The implementing ordinances include a slope density ordinance, lot merger ordinance, density transfer regulations, geologic hazards regulations and other minor amendments to grading ordinances, etc. The San Juan Hills area is approximately two-thirds developed and contains most of the remaining vacant residential land in the City (Figure 4). The planning area contains many valuable natural features such as creeks, dense stands of trees and rock outcroppings and is directly south of Sugarloaf Mountain, a major natural landmark. The vacant land in the area is located primarily on steep slopes and in the canyons, where a combination of severe geologic and flood 827
16 P�CIFIC OCEAN
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SOURCE: City of Belmont.
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hazards constrains development. In addition, infrastr�cture, including roads, drainage facilities, and water and sewer services have not been extended into most vacant areas, partly because of the steep slopes and geologic hazards.
As shown by the lotting pattern in Figure 4, past subdivision in the San Juan Hills area has resulted in very irregular parcelization and highly fragmented ownership of vacant land. Tracts of unsubdivided land in the area are also held in very irregular parcels. Access within the planning area is 1 i mi ted, part i cul arl y to the Skymont Area, and many of the existing paved streets do not meet City standards. Overall, serious natural resource constraints and the pattern of land ownership present major obstacles to quality development and open space preservation in the area.
In response to these constraints and opportunities, the Area Plan assesses the need for open space protection, geotechnical hazard abatement and lot consolidation in the San Juan Hills. It provides a policy framework to define new zoning and subdivision standards, which, through public and private actions, are intended to resolve the development problems and preserve appropriate open space within the San Juan Hills area (City of Belmont, 1986).
The San Juan Hills Area Plan was developed by a special committee appointed by the Belmont City Council in 1983. The planning process involved extensive coordination with community groups and individuals and the recommended goals, objectives, policies and implementation measures of the Area Pl an were developed by the San Juan Committee, City planning staff and interested members of the public.
F o 11 owing pub 1 i c review of the proposed San Juan Hills Area Pl an, the City Planning Commission will make a recommendation to the City Council, which will consider formal adoption of the Area Plan as part of the City of Belmont General Plan. The proposed Area Plan would then augment and supersede where necessary all previous General Plan policies and land use designations pertaining to the San Juan Hills area.
TECHNICAL PROJECT DESCRIPTION
Vacant land in the San Juan Hills area comprises almost one-third of the total land area of approximately 1,000 acres. As shown on Figure 3, existing development in the area is located in three distinct neighborhoods on three plateaus which are known as Skymont, Plateau and Cipriani. There are currently a total of approximately 1,100 dwelling units in the area. The undeve 1 oped 1 and in the area lies between the three plateaus on the steep slopes of Laurel Creek Canyon and San Juan Canyon (Figure 3). Most of the vacant lots are located along unimproved roads and "paper streets" and in 832
21 lsa
larger parcels of land not served by road access ! . Unimproved and paper roads are shown in Figure 4. There are currently a total of 402 vacant lots located on unimproved roads or paper streets in the area, covering a total of 157 acres. In addition, there are approximately 105 vacant lots which are served by improved roads bringing the total of vacant lots in the Area to 504. The Area Pl an groups the vacant parce 1 s in the area into 15 subareas which are defined by their proposed road access. These subareas are depicted in Figure
5. Table 1 depicts the number of current vacant lots and acreage by subarea.
The average slope of vacant land in the San Juan Hills area is extremely high, ranging between 15 percent and 75 percent. Subareas with slopes between 15 and 20 percent inc 1 ude Naughton Avenue and Laure 1 Creek Canyon. Slopes between 20 and 30 percent are found in the Bartlett, Marsten, San Ardo Way, Alhambra, Monte Cresta, San Juan Canyon and Ralston subareas. The Green Court, Marburger (subdivided and unsubdivided}, lower Lock, Upper Lock, and Laurel Creek Road subareas all have average slopes of greater than 30 percent.
The most severe geologic hazards in the planning area are concentrated on both sides of San Juan Canyon and in the eastern reaches of Laurel Creek Canyon. Development in the following subareas would be constrained by the presence of critical geologic hazards: Ralston Frontage, Marburger (subdivided and unsubdivided}, Lower Lock, San Juan Adjacent, San Ardo, Monte Cresta, Alhambra and Naughton.
The planning area poses several problems with existing road circulation.
The Skymont area has only one access/egress {at Christian Drive/Ralston Avenue} and there is no paved road connection or emergency access between the Skymont neighborhood and the rest of the planning area. Many of the existing paved streets in the planning area do not meet City standards for curbs, gutters, and pavement conditions and a large number of streets are unimproved.
Other problems include geologically unstable roads and rights-of-way, the potential for inefficient incremental road development and the lack of onstreet parking. lpaper streets are streets which only exist on the map or as wa 1 king trails. In the San Juan Hills area, these streets are typically located on extremely steep and geologically unstable slopes. Unimproved roads are roads which are used on a regular basis but are built to substandard specifications and are lacking pavement and adequate drainage facilities. {Roadways are shown in Figure 4.)
833
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SOURCE: City of Belmont.
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834
23 lsa
TABLE 1
CURRENT VACANT LOTS AND MAXIMUM BUILDOUT POTENTIAL
UNDER THE SAN JUAN HILLS AREA PLAN
Maximum Maximum
Buildout Buildout
Under Existing Under
Current General Plan2 Area Plan
Subarea Acreage # Lots (# of Units} (# of Units}
Vacant Lots on Unimproved Roads
Green Court 1. 97 12 12 6
Naughton Avenue 6.32 42 42 22
Bartlett Avenue 30.02 110 143 28
Marsten Avenue 3.06 11 15 6
Marburger 6.10 35 35 17
Lower Lock 4.84 28 28 15
Upper Lock 2. 10 13 13 6
San Ardo Way 2.04 12 12 8
Alhambra 8.44 42 42 17
Monte Cresta 7.35 48 48 35
Laurel Creek Canyon
(Unsubdivided) 67.04 12 67 86
Laurel Creek Road 2. 11 9 10 6
Marburger
(Unsubdivided} 11.32 8 11 6
San Juan Canyon
Adjacent 1.49 6 7 3
Ralston Frontage 2.50 _li_ _li 6
Subtotal 156.90 402 499 267
Vacant Lots On Improved Roads
Cipriani (Infill) 70 70 70
Plateau ( Infi 11) -15- -15- 35
Subtotal 105 105 105
TOTAL 507 604 372
!General Plan buildout estimates assume development densities of one lot per acre on unsubdivided land. Potential subdivision of large parcels in the Bartlett Avenue and Laurel Creek Road subareas is accounted for by assuming a 30 percent cover for roads and infrastructure and a 6,000 square foot minimum lot size.
835
24 lsa
As noted above, the San Juan Hi 11 s Area Pl an has been deve 1 oped to account for the unique natural features of the area, the current irregular lotting pattern, geologic and flooding hazards, and infrastructure constraints. To achieve this, the Area Plan sets forth a number of goals, objectives and policies. Implementation of the Area Plan would result in an overall reduction in the permitted densities of development and restrictions on road and infrastructure extension to undeveloped parcels, particularly in areas of steep slopes and geologic hazards. The Area Plan is premised on the following goals and objectives:
0 0
0 0
Geologic Hazards. Ensure a high level of geologic stability for building sites, structures and infrastructure; improve the City's decision-making process regarding geologic hazards; and minimize public liability for hazardous lands.
Natural Resource Preservation. Encourage the preservation of vegetation and other natural resources in the San Juan Hills area; preserve views into, within and from the San Juan Hills area, particularly views of natural areas; and, encourage the preservation of open space in areas of scenic, natural resource or recreational value, as well as in areas susceptible to geologic hazards steeply s 1 oped and susceptible to erosion. Preserve open space in Laurel Creek Canyon, especially the riparian corridor along Laurel Creek.
Ensure that new structures are designed to protect the vi sua 1 and natural resource quality of the hillsides.
Land Use and Site Development. Preserve and enhance the character of existing established residential areas. Achieve a land use pattern that is consistent with the existing slopes and geologic hazards on vacant lands. Minimize buildout of vacant subdivided lots in geologically hazardous areas where it would require major road extensions and improvements, or where it would degrade natural resources and views.
Infrastructure. Ensure that adequate infrastructure is available before permitting development to proceed. Design and -locate infrastructure improvements to protect natural resources and existing neighborhoods. Minimize the City's costs for building and maintaining infrastructure improvements for new development. Ensure that road improvements are geologically safe and do not create traffic safety hazards (City of Belmont, 1986).
Specific policies intended to implement the above goals for future development in the San Juan Hills area are summarized below. These policies 836
25 lsa
are also addressed in the relevant portions of the Environmental Setting, Impacts, and Mitigation Measures chapter of this EIR.
o Geologic Hazards. The Area Plan limits development by establishing land use policies related to geotechnical hazards. Development would not be permitted in any areas with slope instability unless geologic data and engineering solutions assess that development is feasible. No exceptions would be made to this pol icy in areas mapped as having potential debris flow movement or actively moving deep ·landslides. Policies are also set forth to adopt official geologic maps of the San Juan Hills to aid in determining parcel developability and to require specific geotechnical investigations at various stages of development. The permitted density and intensity of development would be related to the slope
characteristics of parcels such that fewer and sma 11 er uni ts on parcels would be permitted as the steepness of the lots increases. (These po 1 i c i es are discussed in greater deta i 1 in the Geology and Soils section of this EIR.)
o Natural Resource Preservatfon. To protect vegetation development would be required to minimize vegetation removal, protect and restore stabilizing vegetation, protect historic and scenic trees, and provide revegetation of all significant tree cover. Streams and creeks would be protected by required setbacks and preventing road crossings. Wildlife habitat would be protected by siting and designing development to maintain portions of existing habitat in a natural state. Grading design standards and restrictions on winter construction would be established. {Refer to the Vegetation and Wildlife section of this EIR.)
o Visual Quality. The Area Plan encourages new development siting and design to protect public views, particularly from Ralston Avenue to Laurel Creek Canyon toward Sugarloaf and San Francisco Bay.
Structures would be encouraged to be sited and designed to maximize view preservation. (Refer to the Visual Quality section of this EIR.)
o Open Space. The Area Plan encourages clustered development wherever possible to leave the maximum portion of a site in its natural state. The Area Pl an encourages creation of an open space buff er between development on vacant parcels in the San Juan Hills and Sugarloaf Mountain. Additionally, a continuous greenbelt of publicly-owned open space should be established.
837
0 26
lsa
Land Use Designations. The Area Plan assigns new land use designations (see Figure 6} to vacant land in the San Juan Hills area and applies slope density regulations and floor area limitations as follows:
(a) Lands adjacent to imp roved roads in a predominant 1 y deve 1 oped residential area are assigned a Low Density Residential {Rl) designation and development on vacant lots is considered infill to the existing neighborhood. In RI areas, one unit could be built on each vacant lot; the maximum size of each unit would be based on the recently adopted FARs (see Appendix B).3 The R-I 1 and use designation is contained in the Be 1 mont Genera 1 Plan and the General Plan policies pertaining to this
designation would continue to govern. Two other 1 and use designations in the Area Plan that are currently contained in the Belmont General Plan are Institutional and Public
Facilities. As with the RI areas, the policies of the Belmont General Plan would continue to govern in these areas.
(b) The remainder of the vacant land in the San Juan Hills planning area is designated Hillside Residential and Open Space (HROP).
The HROP area includes large unsubdivided parcels and land adjacent to unimproved roads which is predominately vacant and suitable for open space or very 1 ow density residential use because of steep slopes, unstable soils, scenic or natural resource value and lack of access. Permitted uses in the HROP area include single family detached dwelling units, other uses which are normally accessory to residential uses, and public and private recreational uses. By purchasing density transfers from owners of lots with critical geologic hazards, owners of safer lots that are closer to existing roads will be able to cluster units and/or develop attached dwelling units. Once density is transferred, the "sending site" is permanently restricted from building. Institutions and public facilities such as churches and schoo 1 s a re permitted with appropriate controls.
3fl oor Area Ratio ( FAR) = tot a 1 gross square footage of development divided by the square footage of site.
838
SOURCE: City of Belmont.
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839
28 lsa
Permissible densities of new development in HROP areas relate to the average slope of the vacant lots. Table 2 presents the slope density formula recommended by the San Juan Committee for use in HROP areas under the Area Plan. Appendix B presents two alternative more and less restrictive slope density tables which were considered by the San Juan Committee. Potential development scenarios using these alternative slope density formulas are evaluated in the Alternatives section of the EIR.
In addition to the slope density restrictions, development in HROP areas would be subject to slope intensity (or FAR) regulations which limit the permitted residential floor area based on the size, slope and location of the lot. Two FAR tables would be used in the HROP areas. One, more moderate formula, would be used to govern the size of residences in areas of moderate geologic hazard. The second, more
restrictive formula would prescribe the amount of square footage that could be transferred from critically hazardous ownerships.
o Lot Merger. The Area Plan promotes the merger of existing contiguous lots held in the same ownership in the HROP areas when one or more of the contiguous parcels does not conform to the minimum lot size required by the slope density restrictions. At least one of the affected parcels must be undeveloped by a structure.
o Lot Reconsolidation. The Area Plan promotes the voluntary reconsolidation of vacant subdivided parcels in HROP areas by encouraging owners along unimproved roads to pool their development capability and resubdi vi de. The Area Pl an part i cul arl y encourages coordinated development to maximize clustering in Laurel Creek Canyon. Landowners who participate in lot reconsolidation are rewarded with additional points in a proposed Allocation System, and can obtain reduced minimum lot sizes or density bonuses. The City would provide techn i ca 1 assistance to 1 andowners and accept open space easements on restricted land to allow property tax reductions. 840
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TABLE 2
SLOPE DENSITY FORMULA FOR HILLSIDE RESIDENTIAL AND OPEN SPACE AREAS Maximum Minimum
Average · Dwelling Units Net Lot Size
Slope per net acre (sq. ft.)
0-9% 7.26 6,000
10% 6.22 7,000
11% 5.38 8,100
12% 4.68 9,300
13% 4.07 10,700
14% 3.57 12,200
15% 3.13 13,900
16% 2.76 15,800
17% 2.45 17,800
18% 2.20 19,800
19% 2.00 21,800
20% 1.85 23,500
21% 1. 73 25,200
22% 1.62 26,900
23% . 1.52 28,600
24% l';.44 30,300
25% 1.36 32,000
26% 1.29 33,700
27% 1.22 35,600
28% 1.16 37,500
29% 1.09 40,000
30% 1.01 43,000
31% 0.94 46,500
32% 0.86 50,500
33% 0.79 55,000
34% 0.73 60,000
35% 0.67 65,000
36% 0.62 70,500
37% 0.57 76,000
38% 0.53 81,500
39% o.so 87,500
40% 0.47 93,500
41% 0.43 100,500
42% 0.40 108,000
43% 0.38 115,500
44% 0.35 123,500
45%+ 0.33 134,000
SOU.RCE: CITY OF BELMONT. 841
30 lsa
o Density Transfer. The Area Plan encourages owners of subdivided lots in critical geologic hazard areas or far from improved roads to sell their permitted square footage to owners closer to existing improved roads. In the unsubdivided areas of Laurel Creek Canyon, the Plan encourages density transfer in exchange for dedication of permanent open space. A tot a 1 of 27 acres in the canyon are designated as "sending sites" from which landowners may sell density. Potential "receiving sites" where landowners can purchase density from sending sites are also designated. The three receiving sites include the 9.1-acre "Horse Ranch" property adjacent to Ralston Avenue and east of the Skymont area, and two parcels totalling 10.8 acres adjacent to the Baptist Church in the Skymont area (see Figure 5). Incentives for the transfer of development rights include additional points in a proposed Allocation System, reduced minimum lot sizes, technical assistance, acceptance of open space easements, and permission to build townhouses and other attached dwelling units.
o Maximum House Size. A maximum house size would be established for vacant, unsubdivided HROP areas.
o Site Development Standards. The Area Pl an encourages design of structures to conform to topography and to be compatible in size and scale with their building site and the predominant character of existing development in the community. Permitted height of structures should reflect lot slope and terracing of homes in hillside areas should be encouraged.
o Utilities. The Area Plan promotes the financing of water sewer and storm drainage utilities to serve the development of private property by the benefiting property owners. Water mains and sewer lines should be located in street rights-of-way for ease of maintenance. The Area Plan encourages storm drainage investigations for new development and the implementation of the recommendations of the Storm Drainage Task Force. (See the Hydrology and Drainage section of this EIR.) The Area Plan also encourages the prohibition of development on creeks and drainage swales and the requirement of storm drainage improvements to direct storm water around structures and into the storm drainage system.
o Road Improvements. The Plan prohibits the extension of roads into areas with moving deep landslides. Improvement of existing unimproved roads and the development of new roads are discouraged on 842
31 lsa
steep slopes where substantial amounts of grading would be required, where major vegetation resources would be removed, and where existing creeks and riparian corridors would be affected. Overall road improvement, plans and financing would be required prior to granting of any building permits on unimproved roads. The Area Plan encourages property owners of vacant subdivided property to develop alternative access plans. New development should finance road improvements. All newly improved roads should be private except for previously dedicated streets. Hillside road standards should be formulated and adopted. The Area Pl an al so sets forth specific provisions for deve 1 opment of road access to property in Laure 1 Creek Canyon, emergency access between the Skymont neighborhood and the rest of the planning area, and 1 imitations on direct access to/from Ralston Avenue.
As out 1 i ned above, the proposed San Juan Hi 11 s Area Pl an estab 1 i shes a pol icy framework which integrates concerns regarding geologic hazards and natural resource protection with a p 1 an for the 1 ocat ion and deve 1 opment of residential units and infrastructure.. Policies of· the Area Plan strictly limit development in geologically hazardous·areas by establishing minimum lot sizes and maximum floor areas dependent �n slope and geologic hazards. This would effectively preclude development on many lots. However, landowners of undeve 1 opab 1 e parce 1 s would be presented with some va 1 ue for their 1 and, as they would be permitted to sell their development rights to other property owners. The Area Plan a 1 so encourages clustered deve 1 opment at the ends of existing roadways in lieu of road extension into undeveloped areas.
Based on the slope density formulas for development in the HROP and R-1 areas, approximately 372 units could be built in the San Juan Hills area under the Area Plan. This is 232 fewer units (38 percent less) than the 604 units permitted under the existing General Plan. The maximum buildout potential of the San Juan Hills area under the existing General Plan and under the proposed Area Plan is shown in Table 1.
Together, lot reconsolidation, density transfer, geologic hazard criteria and road improvement policies of the Area Plan will dictate the location of future development in the area. In general, future development would be concentrated in the less steeply sloped portions of Laurel Creek Canyon, particularly if landowners chose to participate in the density transfer (transfer of development rights) program. Due to the presence of moving, deep landslides, Bartlett Way, Lower Lock Avenue and Naughton Avenue could not be constructed as through streets. In addition, the Area Pl an discourages the development of East Laurel Creek Road and Marsten Avenue as streets open to resident i a 1 traffic. Deve 1 opment of A 1 hambra and Monte Cresta as through 843
32 lsa
streets is also unlikely due to the steep slopes in those areas. Therefore, it is likely that development would occur around the cul -de-sac ends of all of the above streets. Figure 7 illustrates the probable development pattern that would result from implementation of the proposed San Juan Hills Area Plan.
In order to implement the Area Plan, a number of ordinances and implementation actions would be necessary. The precise language and format of these implementation actions are currently under preparation by City staff and consultants and will be brought forward to the Belmont Planning Commission and City Council subsequent to approval of the Area Plan. These actions include the following:
1. Development of Slope Density Ordinance and rezoning of lands designated HROP to Slope Density Zone.
2. Lot Merger Ordinance and merger of lots in areas designated HROP on Plan.
3. Revised Development Standards for FAR, Height, Slope.
4. Slope Intensity Ordinance for Subdivided Parcels on Unimproved Roads.
5. Density Transfer Regulations.
6. Geologic Hazard Regulations.
7. Revisions to Development Standards for Grading, Vegetation Removal, Storm Drainage.
8. Development of Hillside Road Standards.
These implementation actions would involve more specific and detailed information necessary to implement the goals, objectives and policies of the Area plan but would not contain any provisions that would alter the effects of the overall Area Plan.
CONFORMANCE WITH OTHER PLANS AND POLICIES
Belmont General Plan
The Be 1 mont General Pl an, adopted in 1982, is a comprehensive p 1 ann i ng document which provides policies to guide growth and development of land uses, 844
� C]STATISTICAL SUBAREAS
RECEIVING SITES
22 NUMBER OF ADDITIONAL UNITS PER SUBAREA
) i ,, I'. /
,..'\. \.
I\& A TOTAL OF 68 UNITS COULD BE DEVELOPED ON THE THREE RECEIVING SITES - PAPER STREETS AND UNIMPROVED ROADS THAT COULD BE DEVELOPED UNDER SAN JUAN HILLS AREA PLAN (NOTE: It is assumed that existing unimproved roads would remain in use.) : / ·. ·. \'· ... : i ,f',�\, \ \ ! - 11n1 ROADWAY DEVELOPED FOR EMERGENCY ACCESS ONLY ���
ISHOP ROAD
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SOURCE: City of Belmont.
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lsa FIGURE 7 LOCATION OF FUTURE DEVELOPMENT
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845
34 lsa
services and facilities in the City of Belmont. Figure 8 depicts the land use map for the Belmont General Plan. As shown, much of the planning area is designated Low Density Residential {RI). Approximately 25 percent of the area is designated Open Space (OS). In addition, there are small portions of the planning area designated Institutions {In) and Public Facilities {P). The low density residential designation applies to the use of land primarily for single family detached residences. The designation also includes clustered townhouse developments where the overall housing density does not exceed seven uni ts per gross acre. Open space lands are defined in Section 65560 of the State Government Code as any land or water area which is essentially unimproved, and devoted to an open space use including preservation of natural resources, managed production of resources, outdoor recreation and public health and safety. Unsubdivided parcels in the San Juan Canyon area are designated as open space. The General Plan allows for clustered �esidential development not exceeding densities of one unit per acre in these open spaces.
Development should be designed to retain a majority of the land in its natural state. In particular, unstable slopes, slopes over 30 percent, natural drainage ways, stands of trees, and visually prominent ridge tops should be retained in open space. Institutional land use accommodates facilities which provide educational, cultural, religious, health and related services to the community and, in some cases, to a larger service area. The public facilities land use designation applies to areas used primarily for governmental and educational purposes.
The General Plan calls for additional study of the development potential of vacant subdivided and unsubdivided parcels in the San Juan Hills area. The General Pl an states that { 1) the study should evaluate natural and manmade opportunities and constraints in the San Juan Hills area to determine where new residential development can best be accommodated and (2) residential development may occur in clusters leaving significant amounts of vacant land in permanent open space {Section 1010). The proposed San Juan Hills Area Plan has been prepared in response to this General Plan mandate.
The fo 11 owing genera 1 community goals of the General Pl an pertain to future development in the San Juan Hills area {Section 1015):
o Preserve and enhance the attractive, family-oriented and tranquil quality of Belmont's residential neighborhoods.
o Preserve significant open spaces, trees, views, waterways, wildlife habitats, and other features of the natural environment. o Guide the timing and 1 ocat ion of growth and development to ensure 846
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the availability of services and protection of sensitive natural environments.
o Protect persons and property from unreasonable exposure to natural hazards such as floods, fire, unstable ground, erosion and earthquakes.
The proposed San Juan Hills Area Plan establishes policies which are intended to implement the above goals of the General Plan. Overall, the Area Plan policies are more specific than General Plan policies and are focused on guiding development with regard to the unique problems and assets of the San Juan Hi 11 s Area.
The following discussion summarizes the relevant land use policies of the General Plan and evaluates the consistency of the proposed San.Juan Hills Area Plan with these policies.
Poli CY: Intensity of land use should decrease as steepness of terrain and distance from major thoroughfares increase. The lowest intensities of use should occur on the steep hillsides to limit storm runoff, prevent increased erosion, avoid unstable slopes, protect vegetation and watersheds, and maintain scenic qualities. Intensity of use should be governed by considerations of existing deve 1 opment patterns, water and air quality, accessibility, traffic generation, parking, noise, fire safety, drainage, natural hazards, resource conservation and the availability of community facilities and services (Policy 1016.2).
Compliance: The Area Plan incorporates slope density and floor area ratio (slope intensity) tables into its land use policies (see Appendix B).
Application of these formulas decreases the permitted development according to slope and geologic hazards. The Area Plan also includes po 1 i c i es encouraging the retention of permanent open space areas to protect vegetation and other natura 1 resources, inc 1 ud i ng the seen i c resources of the area. Availability of access and public services are also key considerations in permitting development under the Area Plan.
Policy: The following standards shall apply to all new development: (a) sewage disposal shall be by sanitary sewers, (b) storm drainage facilities shall be provided, (c) erosion shall be minimized through runoff retention and revegetation, (d) grading and new impervious surfaces sha 11 be .kept to the mini mum necessary to permit deve 1 opment of land in a manner compatible with its characteristics and designated use, (e) land, water and energy shall be used efficiently, (f) structures shall be clustered, where possible, to maximize open space and minimize 847
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costs of providing public services, (g} safe access to the public road system of the community shall be provided, (h} fire and police protection shall be adequately provided, (i} slopes exceeding 30 percent shall be avoided whenever possible (Policy 1016.4}.
Compliance: The Natural Resource, Land Use and Site Development and Infrastructure policies of the Area Plan address all of the above concerns. Specific policies regarding sewage disposal, road maintenance and fire and police protection are discussed in the Public Services and Utilities section, policies regarding storm drainage are discussed in the Hydrology and Drainage section, and policies regarding slopes, erosion and grading are discussed in the Geology and Soils section of this EIR.
Policy: Natural features, such as ridgelines, canyons, steep hillsides, meadows, streamsides and significant stands of trees, should be preserved and protected through planning, conservation practices and the dedication of open space or scenic easements (Policy 1016.6}.
Compliance: The Area Plan encourages coordinated development of unsubdivided parcels in Laurel Creek Canyon and the transfer of development rights from steep or geologically hazardous parcels throughout the area. The ensuing development pattern would allow retention of significant natural areas in permanent open space.
Policy: No building permits for new structures shall be issued until or unless it has been demonstrated that all necessary public services can be provided within the framework of planned capital and operating budgets of the service agencies. Costs for services which exclusively benefit new development should be borne by that development. Low density residential development of vacant subdivided lots in San Juan Canyon may proceed only when it has been demonstrated that safe development can take place consistent with the po 1 i c i es of the General Pl an, and that adequate access, utilities, fire service and other essential services are available (Policies 1016.7 and 2014}.
Compliance: The Area Pl an requires that the i nsta 11 at ion of water and sewer utilities, storm drainage improvements, and roads to serve the deve 1 opment of private property be financed by the benefiting property owners. Demonstration of the availability of other services would be required in accordance with General Plan policies.
Policv: In any development within the Planning Area, geologic conditions should be thoroughly evaluated to avoid or mitigate problems of unstable land. In no case will development be approved until it has been 848
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demonstrated that buildings and roads will be on geologically stable lands (Policies 1016.8 and 2014).
Compliance: The proposed Area Plan adopts the engineering geologic map and ground movement potential map prepared by William Cotton and Associates in April 1985 as the official geologic maps of the City. In accordance with these maps, any deve 1 opment on s 1 opes steeper than 1 O percent requires a soil and foundation engineering investigation.
Development on lands with highly expansive soils, fill material, or potential landslides or debris flows requires an engineering geologic investigation. The plan adopts a Geologic Hazard Criteria table for use in eva 1 uat i ng the su i tabi 1 i ty of deve 1 opment proposa 1 s. ( Refer to the Geology and Soils section of this EIR for further discussion.) Policy: In low density residential areas, dwelling types should be limited to single family detached. However, clustering or grouping of units may be permitted to preserv$ open space. In steep and environmentally sensitive lands, density may be reduced to protect scenic and open space resources, ensure adequate access and services and avoid geologic hazards. Clustered development at no more than the designated density is permitted on all residential land and shall be required where necessary to meet the policies of the General Plan (Policies 2007.7 and 2009).
Comp 1 iance: The Area Pl an encourages c 1 ustered deve 1 opment wherever possible to leave the maximum portion of the site in its natural state.
Clustering of development is particularly encouraged in Laurel Creek Canyon to preserve resources and efficiently provide infrastructure.
Pol;cy: Single family residences may be built on scattered residential 1 ots that are sma 11 er than the mini mum sizes ca 11 ed for by the Genera 1 Plan (i.e., 6,000 square feet in the R-18 area) if the following conditions are met: (a) access is provided by a public road meeting City standards, (b) buildings and driveways can be located on stable ground, (c) adequate public utilities and services can be provided, (d) adequate fire safety can be assured, (e) at least two off-street parking spaces can be provided, (f) adequate driveway design and access to the public street system can be provided, (g) adequate control of storm water runoff including, if necessary, on-site retention, can be provided (Policy 2007.11)
Compliance: Implementation of the Area Pl an would establish a m1n1mum house size for new development in the San Juan Hills. The slope density and FAR policies in the Area Plan which prescribe the maximum allowable 849
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house size on particular lots may render some substandard lots undevelopable due to size, slope and the presence of geologic hazards.
The Area Plan would, however, provide owners of property which is undevel opabl e under the above standards with a means of transferring their development rights (calculated according to slope density and slope intensity formulas) to other parcels.
Policy: Additional low density residential development may occur on unsubdivided lands in the San Juan Canyon area designated as Open Space on the General Plan Land Use Map. Consistent with this designation, any development in these areas must be clustered preserving most of the land in open space. Development should occur under planned development provisions of the zoning ordinance with density and location of housing units based on thorough evaluation of slope, slope stability, drainage, erosion potential, vegetative cover, adjacent land uses and visual impacts. Safe and adequate provision of access and public services must be assured prior to development approval.
Compliance: The Area Plan reclassifies all land which is currently designated as Open Space in the San Juan Hills area as Hillside Residential and Open Space (HROP) (see Figure 6). Policies are set forth in the Area Plan to restrict residential development of unsubdivided parcels in accordance with natural constraints and to provide the mechanisms by which much of the HROP lands can be preserved as permanent open space.
Zoning Ordinance
Current zoning in the planning area designates the unsubdivided lands in Laurel Creek Canyon, adjacent to Bartlett and adjacent to Marburger as "Agriculture and Open Space", with a one-acre minimum lot size. Subdivided areas are designated "Residential-18" which imposes a 6,000 square foot minimum lot size on new subdivision, but does not impose a minimum lot size for building permits on existing lots.
The following discussion evaluates the relationship of proposed Area Plan policies with the site development standards for the R-18 district imposed by the Zoning Ordinance.
Policy: Floor Area Ratios (FAR). This schedule governs the size of buildings in relation to the average slope of the building site. The FAR is intended to prevent oversized houses, and decreases the ratio between 850
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lot size and house size as the lot size increases. The existing FAR permits a minimum floor area of 1,200 square feet in all R-1 zoning districts and maximum floor areas of between 3,500 and 4,500 square feet. {Section 4.2.3.d).
Compliance: The proposed Area Plan would establish three sets of FARs for Low Density Residential and HROP areas {see Appendix 8). The following changes are integrated into the proposed FARs: {a) the whole building envelope is considered when measuring floor area, {b) a FAR formula which is more restrictive than that applied to Low Density Residential areas is used for lots which have moderate geologic hazards to create an incentive for property owners to combine lots, {c) a very restrictive formula is applied to lots with critical geologic hazards to create a mechanism by which owners can transfer their permitted floor area to owners of lots in more geologically stable lots.
Policy: Minimum Setback Standards. The Zoning Ordinance provides that lots have a minimum average width of 60 feet in the R-18 zone, and a minimum street frontage of 50 feet. (Sections 4.2.3.b,. 4.2.3.c).
Setbacks for front yards are 15 feet. Setbacks for interior lots are to be 10 percent of the lot width, and not less than 6 feet or greater than 9 feet. Corner lots have required setbacks of 15 feet {Sections 4.2.4,
4.2.5.c, 4.2.6).
Compliance: The proposed Area Plan does not contain any policies which would ·conflict with the minimum setbacks established in the Zoning Ordinance. The Area Plan requires an additional setback from riparian corridors.
Policy: Building Height. A maximum building height of 28 feet is permitted in the R-1B zone {Section 4.2.3.e). Building height is measured from finished grade around the perimeter of the building to the uppermost portion of the roof for each respective cross-s 1 ope section of the building (Section 2.67).
Compliance: The Area Plan establishes site development standards which would be imp 1 emented by ordinance to ensure that structures conform to the site topography and are compatible in size and scale with the bui 1 ding site and the predominant character of existing deve 1 opment in the community. The height and bulk restrictions for structures in hillside locations as well as design guidelines to ensure that large vertical surfaces and roof surfaces are broken up and to encourage terracing would be established.
852
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Policv: Parking Requirements. A m1n1mum of two garage spaces (360 square feet) are required for each dwelling unit (Section 8.4.1) Compliance: Although the Area Plan would estabH sh new road standards for access in hillside areas, on-site parking requirements would remain the same. However, on-street parking would be encouraged to be provided in parking bays at intervals along the road to facilitate the construction of narrower roads in steep locations.
Growth Management Program
The City of Belmont has a competitive rating system by which applications for new development are evaluated. The growth management system is intended to provide for a rate and quality of residential growth which is consistent with the goals and policies of the General Plan and is coordinated with the provision of needed public improvements and services. The rating procedure evaluates proposed developments based on the size of the building in relation to the slope of the property, the amount of grading necessary, the height of the structure, setbacks incorporated into project design, proposed landscaping and the ability of public agencies to provide services.
The proposed San Juan Hills Area Plan includes policies which provide landowners with additional points in the Allocation System for participating in overall resubdivision or purchasing transferred density.
RELATIONSHIP TO OTHER PLANNED PROJECTS
The Area Plan is consistent with the Belmont General Plan and policies of both documents would apply to all future projects in the San Juan Hills area.
In instances where the Area Plan provides more specific policies, these would supersede the policies of the General Plan.
In tot a 1, the Area Plan would permit deve 1 opment of a maximum of 372 residential units in the planning area (see Table 1). Of these, approximately 68 could be developed on the "Horse Ranch" property and/or in the vicinity of the Baptist Church in the Skymont neighborhood. The Allocation System of the City's Growth Management Program limits the issuance of building permits to 56 per year. All development permitted under the Area Plan would compete with other proposed projects in the A 11 ocat ion System for the 1 i mi ted number of permits.
853
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JURISDICTIONAL AND PERMIT-GRANTING AGENCIES
As the lead agency, the City of Belmont would have sole responsibility. for approval of the proposed San Juan Hills Area Plan. In addition, the following agencies and groups would have an interest in the project and/or would have approval authority over specific development projects in the planning area:
U.S. Army Corps of Engineers
U.S. Fish and Wildlife Service
California Department of Fish and Game
California Department of Transportation (Caltrans)
Association of Bay Area Governments
City of San Mateo
San Mateo County
Belmont County Water District
South Bayside System Authority
South County Fire District
854
43 ENVIRONMENTAL SETTING, POTENTIAL IMPACTS AND
MITIGATION MEASURES
LAND USE AND POPULATION
Setting
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The 1,000-acre San Juan Hills area is located on the eastern slopes of the Santa Cruz mountains in the City of Belmont (Figures I and 2). Land uses in the area a re comprised of a mixture of resident i a 1 and open space uses which extend from Ralston Avenue to the foot of Sugarloaf Mountain to the north. The residential uses are concentrated in three distinct areas, which are defined geographically by their plateau locations and distinguished by their access from Ralston Avenue. As shown on Figure 3, the Skymont area is 1 ocated on the western edge of the San Juan Hi 11 s area and is accessed by Christi an Ori ve. The Plateau area is centrally 1 ocated and is accessed by Hillcrest Drive and Belmont Canyon Road. The Cipriani area forms the eastern part of the project area and is accessed by Cipriani Boulevard. These three areas are separated by two steep canyons. Laurel Creek Canyon, 1 ocated between the Skymont and the Plateau areas, originates at the "Horse Ranch" property on Ralston Avenue. It drains north to the base of Sugarloaf Mountain and then east, forming the northern boundary of the San Juan Hills area. San Juan Canyon is located between the Plateau and Cipriani areas and joins Laurel Creek Canyon to the north.
There are currently approximately 1,100 residential units in the project area. Residential development in the San Ju·an Hills area has occurred in a piecemeal fashion over the past fifty years. Hi stori ca 11 y, the Plateau and Cipriani areas were subdivided into hundreds of small substandard lots {most under 9,000 square feet in area) which were distributed as door prizes at a local theater. The existing range of housing types and sizes in these areas results from the unplanned fashion in which they were developed. Older development is comprised primarily of modest single-family dwellings, located on the p 1 ateaus and gent 1 e slopes. More recent deve 1 opment is comprised primarily of larger single-family dwellings which are located on steep slopes and in areas with constrained access. The Skymont area was developed about twenty years ago as a single subdivision. For the most part, dwelling units in the Skymont area have adequate access and standard lot sizes and are located on stable land.
At present, about one third of the planning area is undeveloped. There are 105 vacant lots which are located on improved roads. The remaining vacant land in the San Juan Hills area is located in areas which are constrained by steep slopes, geologic hazards and inadequate access. As shown in Figure 4, 855
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vacant land is located primarily in the canyons between the three plateaus and along the northern edge of the project area. In total, there are approximately 157 acres of vacant land which are divided into 402 parcels on unimproved or "paper" streets (see Table 1). Much of the land adjacent to unimproved or paper streets has been subdivided into parcels which range in size from 1 ess than 6,000 square feet to over 65,000 square feet. Large tracts of unsubdivided land, accounting for nearly half of the total undeveloped acreage in the project area, are located in Laurel Creek Canyon and south of Marburger Road.
Under the Belmont General Plan (1982), developed areas and vacant subdivided areas in the San Juan Hills are assigned a land use designation of Low Density Residential, R-1, and unsubdivided areas are designated for permanent Open Space, OS (Figure 8). The General Plan allows development of vacant lots in the San Juan Hills area only after it has been demonstrated that "adequate access, ut i 1 it i es, fire service and other essential services are available ... and that buildings and roads will be on geologically stable lands" (Policy 2014). Development in the areas designated Open Space must be clustered to preserve prominent natural areas. The Zoning Ordinance allows one unit per lot in the R-1 areas and one unit per acre in the Open Space areas. Further subdivision of R-1 lots is possible provided adequate services and infrastructure can be supplied.
Existing land uses adjacent to the San Juan Hi 11 s area are varied. To the west, bordering the Skymont neighborhood, the project area is bounded by residential and open space uses. To the north, the project area is bounded by Sugarloaf Mountain, which is in the City of San Mateo and is currently undeveloped. To the east, the Cipriani neighborhood is bounded by other residential uses in the City of Belmont. Ralston Avenue forms the southern boundary of the project area and is flanked by a variety of land uses.
Community commercial uses (gas station, supermarket, drugstore) are located at the intersection of Ralston Avenue with Alameda de las Pulgas; professional offices and apartments are at the intersection with Cipriani Boulevard, a research and development park at Davis Street; Ralston Intermediate School at Tahoe Street; a church at Lassen Street; and townhouses at Hallmark Street.
To the south of Ralston Avenue across from the Skymont neighborhood, City of San Francisco watershed lands {in unincorporated San Mateo County) are held in permanent open space.
In 1980, the total population of the City of Belmont was 24,500 persons.
With 1,100 existing units in the San Juan Hills area and an average household population of 2. 4 persons per unit, the planning area has a population of approximately 2,640 persons (U.S. Census Data, 1980). Under the existing General Plan, approximately 604 new residential units could be built in the 856
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San Juan Hills area (see Table I and Figure 7). Assuming 2.4 persons per unit, this development would be accompanied by a population increase of approximately 1,450 persons. This would represent a 55 percent increase in the population of the San Juan Hills area and a six percent increase in the citywide population.
Potential Impacts
The proposed San Juan Hills Area Plan would supersede the existing Genera 1 Pl an in terms of guiding future development in the San Juan Hi 11 s area. The major land use differences of the proposed Area Plan compared to the existing General Plan would be in the location of development,· the densities of development and the total buildout potential. Overall, the Area Plan would result in a lesser level of impact than the General Plan since the amount and location of development would be premised on environmental constraints.
Change in Land Use Designations. The Area Plan assigns two basic land use designations to the project area (see Figure 6). All lots which have access to improved roads are designated Low Density Residential (R-1}. Other lands are designated Hillside Residential and Open Space (HROP). The Area Plan establishes policies which apply to development in each of these districts. Development in both the R-1 and HROP areas is subject to policies which establish slope density and floor area ratios. The HROP areas are also subject to additional policies which 1 imit development based on geologic hazards, access constraints, and provision of infrastructure.
Overall, the changes in land use designations result in a redistribution of development potential. The land use designations for substantial portions of the planning area would be changed from low density residential (R-1} to Hillside Residential and Open Space (HROP}, where much lower development densities are permitted. Overall, the new Area Plan permits less development and concentrates that development in geologically stable areas. Figure 7 depicts a potential development pattern under the Area Plan indicating number of units by subarea and potentially developable paper streets.
Additional land use designations in the planning area include Public Facilities (P) and Institutional (IN} (see Figure 6). These designations are unchanged from those shown in the General Plan.
Reduced Bui 1 dout Potent i a 1 . Under the Area Pl an, a maxi mum of 372 residential units could be developed in the San Juan Hills area (see Table I and Figure 7}. This is 38 percent fewer than the 604 units permitted by the Genera-1 Pl an. It should be noted that under either of these p 1 ans, however, 857
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the actual bu i l dout potent ia 1 when a 11 geo 1 og i c, access and service constraints and the slope intensity (FAR) regulations are addressed could be substantially fewer than the maximum buildout estimates.
The more restrictive Floor Area Ratios (FAR) instituted in the Area Plan would severely limit development on very small and/or geologically hazardous lots. The establishment of minimum house sizes would render many of these lots undevelopable under the Area Plan. Such ownerships would be eligible for the density transfer program. Successful implementation of the land use policies and programs of the Area Plan would result in preservation of a substantial amount of open space in the planning area.
Location of Development. Under both the Area Plan and the General Plan, approximately 105 residential units could be built as infill development in the Plateau and Cipriani neighborhoods and the remainder would be distributed throughout the undeveloped portions of the San Juan Hills area. As shown in Table 1, the distribution and number of units among the subareas under the Area Plan is significantly different than under the General Plan.
The greatest differences in the 1 ocat ion of future deve 1 opment would occur in the Bartlett and Laurel Creek Canyon subareas. Under the Area Plan, 1 andowners in the Bartlett area would be encouraged to merge their 1 ots.
There are 110 lots in the area with a potential for development of 143 units under the existing General Plan. However, there are only 20 separate ownerships so a great deal of lot merging could occur. The Area Plan would permit a maximum of 28 uni ts in the Bartlett subarea. In the Laurel Creek Canyon subarea, which is currently unsubdivided, the Area Plan would permit development of 86 units, as opposed to the 67 under the General Plan.
Development Densities. Under the Area Plan, development densities would be expected to approximate existing densities in the planning area except in the unsubdivided areas (particularly Laurel Creek Canyon) where significantly lower densities would be est ab 1 i shed. Al though the Pl an designates three sites in the Laurel Creek Canyon subarea as "receiving sites" for transfer of development rights, the Plan limits the maximum amount of density transferable to double the maximum number of units permitted by the slope density regulations. The maximum number of units permitted on the "Horse Ranch" would be 28, the maximum on the Baptist Church parcel would be 20 and the maximum on the adjacent parcel would also be 20, with resulting densities of between three and six units per acre.
It is assumed that most of the paper streets in the planning area would be developed as cul-de-sacs due to existing geologic hazards and the extensive amount of grading required to develop roads on steep terrain. If the Area 858
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Plan is fully implemented lot mergers, resubdivision, and density transfers in the subdivided hillside areas would result in development of clustered units at the ends of cul -de-sacs. Clustered development would be encouraged by allowing reduced minimum lot sizes and density bonuses.
Population. The 372 residential units which could be developed under the proposed Area Pl an would result in an increase in the population of the planning area and the city, as a whole. A population increase of approximately 893 persons would result from buildout under the Area Plan.
This would represent a 30 percent increase in the population of the San Juan Hills, and a three percent increase over the current citywide population of 24,500. Si nee the proposed Area Pl an permits fewer uni ts than the existing General Rlan, this increase in population would be less than that which would occur with full buildout of the San Juan Hills under the General Plan.
Mitigation Measures
The following measures are recommended to offset potential adverse impacts resulting from development under the proposed Area Plan:
1. The City should take an active role in encouraging participation in the lot merger, resubdivision and density transfer programs of the Area Plan. The City should develop informational literature and provide technical assistance to landowners in the subareas to help facilitate lot mergers, resubdivision and density transfer.
2. Where development at the ends of cul-de-sacs would result in densities of development which are significantly greater than nearby uses (i.e., townhouses, attached units, etc.), buildings should be designed to promote visual blending. The siting of buildings and landscaping should be sensitive to ex'isting view corridors from surrounding residential areas.
859
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GEOLOGY AND SOILS
Setting
The San Juan Hi 11 s planning area encompasses three northward-plunging ridges and two intervening canyons {Laurel Creek and San Juan Creek) in the footh il 1 s of the Coast Range in the northwestern portion of the City of Belmont. Elevations range from approximately 150 feet where East Laurel Creek leaves the planning area to 600 feet at the southernmost end of the central ridge.
Bedrock underlying the site consists of several rock types of the Franciscan Complex (William Cotton and Associates, 1985). Most of the project area is underlain by sandstone, with chert underlying the eastern ridgetop and the highest part of the central ridge (Figure 9). Small bodies of greenstone and serpentinite are mapped in the western canyon (East Laurel Creek) and Franciscan "melange", a sheared mixture of several rock types, is mapped as underlying the uplands in the southwestern corner of the project area.
The sandstone can be quite stab 1 e if bedding p 1 anes or fracture p 1 anes are oriented favorably with respect to slopes. Unfavorable fracture planes or finer-grained silty interbeds can decrease stability of sandstone slopes. The greenstone and melange of the Franciscan complex are typically highly fractured and not very stable in steep slopes. The chert is a very hard, but brittle, material. The serpentinite is generally of poor stability on slppes.
Surface soi 1 s of the project area are largely dependent on the underlying bedrock materials. The sandstone weathers to a clayey silty sand or sandy silty clay soil that is moderately expansive (seasonally expands when wet and shrinks when dry). The chert typically weathers to a rocky, clayey sand. The sheared material of the melange weathers to a highly expansive silty clay.
The greenstone typically produces a rocky, silty clay soil that is moderately to highly expansive. The serpentinite weathers to a highly expansive clay soil.
The U.S. Soil Conservation Service, in a generalized map of San Mateo County soils (Soil Conservation Service, 1974) identifies two primary soil types in the project area. Most of the central portion of the site, including the stream valleys, is mapped as the Gaviota-Los Gatos-Gilroy association.
This is considered to be a relatively shallow soil (18 to 30 inches to bedrock) with moderate erosion hazard. The Montara-Climara association is mapped in the western part of the project area, where the melange and serpentine bedrock occur. These soils are shallow to moderately deep and are highly erosive on steep slopes.
860
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lsa FIGURE 9 GEOLOGIC FEATURES
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50 lsa
A Geologic Hazards Analysis Report for the San Juan Hills area prepared by William Cotton and Associates maps surficial deposits, including several types of landslides. Alluvial deposits of river-lain gravel, sand, silt and clay lie along the valley bottom of Laurel and San Juan Creeks. The creeks are generally incised into the landscape, with steep banks. Colluvium, the accumulation of soil and rock debris moving downhill by the force of gravity, mantles the bases of slopes and fills sha 11 ow swa l es on the side s 1 opes of canyons. The poorly consolidated material of colluvium is subject to landsliding. In particular, colluvial-filled swales, when subjected to intense rainfall can fail as rapid debris flows, posing hazards to the safety of persons and property below. Several debris flow scars have been mapped in the planning area, including nine scars younger than approximately five years, and six older scars. These are located on steep side slopes above both Laurel and San Juan Creeks. In addition, deep deposits of colluvium at the bases of slopes are subject to deeper, slower-moving landslides. Several active landslides as well as dormant and long inactive landslides are mapped on side slopes in the planning area.
The San Andreas fault is approximately one mile from the project area and is the most significant fault posing a hazard to the San Juan Hills area. A repeat of the 1906 earthquake on the San Andreas fault would be expected to produce Modified Mercalli intensities of VIII or IX or possibly higher in the San Juan Hills area. Intensities of VIII can cause chimneys and some walls to fall, and intensities of IX are strong enough to shift buildings off of foundations and break underground pipes. Such an event on the San Andreas fault is expected to occur, on average, once every 100 to 300 years.
Groundshaking of such high intensity would also likely cause landsliding in the planning area. Landsliding was reported in the area in 1906. A U.S.
Geo logical Survey map (Wieczorek et al . , 1985) of the risk of earthquakeinduced landsliding in San Mateo County shows a moderate risk for most of the canyon side slopes in the project area and a high risk for the slopes of the upper reaches of Laurel Creek, in the western part of the planning area.
The William Cotton and Associates report integrates the information from its map of engineering geologic features into a "Ground Movement Potential Map", which is included in the San Juan Hills Area Plan as the Geologic Hazard Policy Map (Figure IO). This map generally identifies unstable or potentially unstable ground on all of the side slopes of Laurel Creek and San Juan Creek.
Virtually all of the designated stable areas on ridgetops are currently developed. Most of the undeveloped areas are unstable or potentially unstable. Many currently developed areas at the crests of slopes are also within zones mapped as being potentially unstable. These include areas along Marsten Avenue, Skymont Drive, Belmont Canyon Road, Upper Lock Avenue, Lower Lock Avenue, Plateau Drive, and Beresford Avenue. In addition, substantial 862
SOURCE: City of Belmont.
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FIGURE 10
DSbr DEVELOPMENT AND ROAD mSun EXPANSION PERMITTED
Sex DEVELOPMENT AND ROAD
Sff EXPANSION CONDITIONALLY
Pfs PERMITTED
F',��:1:
-p�
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DEVELOPMENT AND ROAD
EXPANSION NORMALLY NOT
PERMITTED UNLESS HAZARDS
ARE MITIGATED
RESIDENTIAL DEVELOPMENT
NOT PERMITTED UNLESS
CONDITION IS DEMONSTRATED
NOT TO EXIST OR
ELIMINATED.
ROAD EXPANSION NORMALLY
NOT PERMITTED UNLESS
HAZARDS ARE MITIGATED
DEVELOPMENT AND ROAD
EXPANSION NOT PERMITTED
UNLESS CONDITION IS
DEMONSTRATED NOT TO EXIST
OR IS ELIMINATED
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NORTH
feet 1000
I I SCALE
GEOLOGIC HAZARD POLICY MAP
u, 1----4
863
52 lsa
port i ans of the developed hil 1 s east of San Juan Boulevard are mapped as potentially unstable. The immediate valley bottoms of Laurel and San Juan Creeks are considered stable, because of flat slopes. This includes currently undeveloped areas along Laurel Creek as well as paved roadway areas along East Laurel Creek Road and San Juan Boulevard. The side slopes immediately adjacent to the valley bottoms are potentially unstable, however, and pose a threat to properties at their base. There are currently three active landslides affecting properties on the west side of San Juan Boulevard.
According to the San Juan Hills Area Plan, of 419 dwelling units currently permitted in the planning area on vacant subdivided lots, four percent are on relatively stable ground, 88 percent on potentially unstable ground (including 58 units in potential debris flow areas), and eight percent on actively unstable ground (City of Belmont, 1986).
Potential Impacts
Over a 11, the proposed Area Pl an provides a more comprehensive set of policies regulating development in areas with geologic hazards than currently exist under the General Pl an. The 1 ocat ion of future development under the Area Plan would be restricted according to potential geologic hazards identified in the William Cotton and Associates report. The Plan establishes a slope density formula which limits allowable densities based on lot size, slope and the presence of geologic hazards.
Full buildout of the proposed project would add 372 additional residential units to the San Juan Hills planning area (see Table 1 and Figure 7). Although this is substantially less development than could occur under the Genera 1 Pl an, this deve 1 opment would result in a significant amount of ground clearing and grading in the San Juan Hills area. New development throughout the planning area would be at lower densities and would be located along extended roads and cul-de-sacs. Grading associated with hillside stabilization, road construction and building pad excavation would result in alteration of the natural topography of the San Juan Hills area. Construction of the residences and roads could result in increased erosion rates and sedimentation in drainage facilities (see the Hydrology and Drainage section of this EIR).
Virtually all of the units would be located on or immediately downslope of potentially unstable slopes, according to the Geologic Hazard Policy Map.
This development would be in danger of damage if hazards are not properly mitigated. Residences 1 ocated below potential debris flows would present potent i a 11 y 1 i fe-threaten i ng hazards. If improperly designed, deve 1 opment could increase landslide risks by altering drainage patterns, undercutting the bases of slopes, or loading the tops of slopes.
864
53 lsa
The Area Pl an includes consideration of these potent i a 1 hazards. It proposes to officially adopt the William Cotton and Associates maps for determining the relative stability of land when reviewing development applications and public works improvements. Specifically, the Area Plan proposes to:
o Require soil engineering and engineering geologic investigation for steep and potentially unstable lots, and require recommended mitigations as conditions of approval.
o Adopt land use policies that permit uses, permit uses with conditions, or ·do not permit uses within each designated geotechni cal hazard zone. Permitted uses by geo 1 ogi c hazard zone are identified in Table 3. Structures and roads are generally not recommended to be permitted on active landslides or potential landslides unless geologic data and/or engineering solutions permit the use.
o Require mitigation of geologic hazards prior to development of roads or structures in areas with moderate hazards.
o Restrict development in critical geologic hazard areas. Prohibit new residences in potential debris flow areas and prohibit structures in active deep landslide areas, unless the hazards are removed.
Normally, mitigation of landslide hazards would consist of significant site alteration. As a minimum mitigation would likely include collection of surface and subsurface drainage. In addition, large active and potentially active slides would likely need to be excavated and recompacted. Potentially unstable slopes would have to be regraded and partially reconstructed in order for development upon them to be considered safe. Retaining walls, diversion structures, partial slope excavations, and drainage terraces would be other possible mitigative actions. Slopes would also need to be stabilized for severe seismic shaking. These types of activities could be very costly, and significant grading could result in vegetation removal, increased erosion and large unnatural slopes. The cost of stabilizing areas to enable extension of public roads could also be significant.
Seismic shaking from an earthquake emanating from the San Andreas fault could also affect structures and slopes in the San Juan Hills planning area.
Severe shaking could damage structures that are not built to very high standards of seismic design. Seismic shaking could a 1 so trigger numerous 865
54 lsa
TABLE 3
GEOLOGIC HAZARD CRITERIA FOR DEVELOPMENT
SYMBOL GEOTECHNICAL
PARAMETERS
Sbr Bedrock with thin soil
Sun Unconsolidated sediment
Sex Highly expans�ve soil
Sff Fill on nearly flat ground
Pfs Potential settlement or failure of fill on a
moderate slope
Ps Potential shallow ( 10') landslide failure
Pd Potential deep ( 10') landslide failure
Ms Actively moving shallow ( 10') landslide
Pdf Potential debris flow movemt:;1t
Md Actively moving deep ( 10') landslide
Y Yes (permitted)
r The land use would normally be expected to be permitted. provided the geologic data and/or engineering solutions are favorable.
However, there will be instances where the use will not be appropriate.
N• The land use would normally be expected not to be permitted.
However, there will be circumstances where geologic data and/or engineering solutions will permit the use.
SOURCE: WILLIAM COTTON AND ASSOCIATES, 1985.
LAND USE
Residential Roads
1 uniV 7 units/ Planned Public Private Water
acre acre Development Tanks
y y , y y y y
y y y y y Y"
r y• y• y y Y"
r y• y• Y" r Y"
Y" r y• y• y• N"
N• N• w N• N. N•
N• N· N. N• N* N"
N• N. N" N' N' N'
N N N N· N· N
N N N N N N
N No (not permitted). The map must be changed to show that this hazard does not exist before development will be allowed. The map change must be based on a demonstration that the map was in error or that improvements have been undertaken which change the geology and remove the hazard.
866
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landslides that could damage property and 1nJure residents. Landslide mitigations designed to reduce rainfall-induced slides (such as reconstructed slopes, drainage structures, and retaining walls) could be damaged if not adequately designed for seismic shaking.
Mitigation Measures
The following measures are recommended to offset adverse geologic impacts in the planning area:
I. The recommended land use policies of the William Cotton and Associates April 1985 report should be included in the implementing ordinances for the Area Plan. This includes adherence to the geologic hazard criteria shown in Table 3. The Engineering Geologic Map and Ground Movement Potent i a 1 Map should be included in the implementing ordinance as the official geologic maps of the City.
Modi fi cat i ans of these maps should be poss i b 1 e, if warranted by supporting data and approved by the City Geologist.
2. The implementing ordinance for the geologic hazards policies of the Area Plan should include the recommendations in the William Cotton and Associates report for required geologic and geotechnical investigations. This includes soil and foundation engineering investigation by a registered civil engineer for proposed development on a 11 s 1 opes steeper than IO percent, as we 11 as in areas of expansive soils or other potential foundation problems. In addition, applications for development on all unstable or potentially unstable areas should include investigations by both an engineering geologist and a soils engineer.
3. The geologic hazard ordinance should specify that the scope of soil engineering and engineering geologic investigations should follow the guidelines recommended on pages 37-38 of the William Cotton and Associates April 1985 report as well as any additional standards and guidelines developed by the City. In addition, slope stability studies should be based on quantitative analyses and should address expected seismic conditions. The results of the investigations should not only be reviewed by a geologist hired by the City, but also by a soils engineer.
4. The geologic hazards ordinance which will implement plan policies should require that soils engineers and engineering geologists submit project completion reports stating that plans, grading operations, and foundation excavations are in accordance with their 867
56 lsa
original recommendations. They should also be required to submit comp 1 et ion reports that describe the f i na 1 "as-bu i 1t" condition of the construction project. As noted in the William Cotton and Associates report, technical plan review, field inspections and the comp 1 et ion report are very important e 1 ements of the geotechn i ca 1 review procedure.
5. The implementing ordinances for the Plan should prohibit grading activities during the winter rainy season from October 15 - April
15. 868
57 lsa
HYDROLOGY AND DRAINAGE
Setting
Most of the San Juan Hi 11 s planning area drains to East Laurel Creek.
The drainage area for this creek is approximately 630 acres {Figure 11}.
Runoff is collected from developed areas in storm drains and then flows through the open channel of East Laurel Creek. Along San Juan Boulevard, drainage flows along the street, into storm drain inlets, and then into San Juan Creek, which empties into Laurel Creek. A narrow strip of the far western part of the planning area drains into the main channel of Laurel Creek (Figure 11} . East Laurel Creek eventua 11 y flows into Laurel Creek, through the City of San Mateo, and its runoff is then directed into the Bay.
The storm drainage system has been inadequate to handle runoff from severe storms in recent years, causing localized flooding problems. In addition, houses have been built over San Juan Creek, decreasing the Creek's capacity to carry large flows. Storm drain pipes are too sma 11 in many locations, and there are too few inlets. The pipes and inlets are often blocked by soil or debris, thereby decreasing capacity. Vegetation clearing and earthwork associated with recent development have caused erosion of steep slopes, further adding to downstream sedimentation and blockage of drainage structures.
The City formed a Storm Drainage Task Force to identify storm drainage problem areas in the City and to recommend improvements. These improvements and their costs are detailed in an engineer's report to the City (CH2M Hill, 1986). Several improvements are proposed for the San Juan Hills planning area (Figure 12). The most significant proposed improvement in the planning area is a new 30-inch to 42-inch storm drain line to parallel existing improvements on San Juan Boulevard. A new 36-inch line is also proposed for Ponce Avenue, and new 1 ines are proposed to collect runoff from Sequoia Way and Haskins Drive to an outfall into East Laurel Creek. A major aspect of the proposal is to build downdrains to collect runoff from the higher elevation streets, such as Belmont Canyon Road, Barclay Way, and Alhambra Drive to the trunk lines on San Juan Boulevard.
Potential Impacts
Development under the proposed Area Plan would result in approximately 38 percent 1 ess development than under the existing General Pl an. Therefore, there would be 1 ess runoff and erasion resulting from development under the Plan than would occur under the General Plan. Nevertheless, if the proposed planning area were fully built out to 372 units, approximately 20 acres of 869
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lsa -FIGURE 11 LAUREL CREEK WATERSHED
870
59 lsa
impervious surface would be added to the watershed of Laurel Creek. This would increase peak flows at the mouth of East Laurel Creek by approximately 25 percent for the IO-year event and 15 to 20 percent for the 25-year event . . These runoff increases could result in increased bank eras ion a 1 ong East Laurel Creek and Laurel Creek, possibly triggering a cycle of bank erosion and bed sedimentation propagating further downstream. Locally, slope areas adjacent to the new impervious surfaces could be affected by increased flows if drainage is not properly designed. Increased flows focused onto slopes could cause slope erosion and could trigger landslides. New structures could be affected by localized flooding if on-site or uphill drainage design is inadequate. New structures adjacent to streams could be affected by flooding or bank erosion.
The storm drainage .improvements proposed by the Storm Drainage Task Force would reduce existing localized flooding problems. They would also reduce hillside erosion and reduce the potential for landsliding on a number of slopes. They would, however, incrementally increase peak flows in downstream areas of Laurel Creek.
In addition to the Storm Drainage Task Force recommend at i ans, the San Juan Hills Area Plan also proposes to:
o require storm drainage investigations by applicants for new development;
o prohibit development on creeks or drainage swales;
o require improvements to direct storm drainage around structures; and o require benefiting property owners to finance needed storm drainage improvements.
If properly enforced, these proposed requirements would mitigate most localized storm runoff prob 1 ems. Deve 1 opment in the planning area would, however, still result in increased peak flows downstream.
Mitigation Measures
The following measures are recommended to offset potential adverse impacts resulting from development under the proposed Area Plan:
I. The storm drainage improvements recommended by the Storm Ora i nage Task Force should be adopted and implemented.
871
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NORTH
0 feet 1000
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lsa FIGURE 12
STORM DRAINAGE IMPROVEMENTS
°' 0
872
61 lsa
2. A storm drainage investigation should be conducted which addresses not only localized drainage in the San Juan Hills area, but al so downstream effects. This study should evaluate potential increased peak flows in Laurel Creek and the potential for creekbank erosion and deposition downstream. The possibility of developing a series of check dams to capture silt and check erosion and/or developing retention basins to decrease peak flows should be addressed. This study should be prepared in coordination with the City of San Mateo.
This study could be done as part of the recently authorized EIR on the San Juan Boulevard Stormdra ins and the Downdra ins in San Juan Canyon and East Laurel Creek.
3. Drainage should not be directed onto unprotected slopes or creek banks. Where runoff must flow from impervious surfaces onto natural ground, proper energy dissipation structures should be provided.
4. If the western canyon area (upper elevations of East Laurel Creek Canyon) is developed, drainage design should include downdrains similar to those proposed for San Juan Canyon.
5. The City should develop guidelines for minimum setbacks for structures from San Juan and East Laurel Creeks. Creek setbacks should be a mini mum di stance of 2 1/2: 1, horizontal to vertical , from the creekbed or as specified by the City Geologist and should include a working area for maintenance.
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VEGETATION AND WILDLIFE
Setting
The San Juan Hills planning area covers approximately 1,000 acres on the eastern flanks of the coastal range in the City of Belmont. The San Juan Hills area includes a substantial amount of open space within the City of Belmont and is adjacent to Sugarloaf Mountain in the City of San Mateo (see Figure 3).
Vegetation. Approximately one third of the San Juan Hills planning area is undeveloped and covered with vegetation typical of foothill areas on the San Francisco Peninsula. Approximately half of the undeveloped portion of the San Juan Hills is located in Laurel Creek Canyon. The remainder is located northwest of Bishop Road; on the western side of San Juan Canyon; and on the southern side of 1 ower Laurel Creek Canyon. (Major features are shown in Figure 3.)
Four vegetation types occur in the undeveloped portions of the San Juan area: annua 1 grass land, chaparra 1 , mixed evergreen woodland and riparian woodland. The pattern and location of vegetation types in the San Juan Hills planning area are shown in Figure 13. Appendix C includes a list of observed and potential vegetation species in the San Juan Hills area.
Annual grassland covers about 25 percent of the vacant land in the San Juan Hills planning area and about half of Sugarloaf Mountain, which is adjacent to the San Juan Hills planning area. It occurs at relatively high elevations on south- and west-facing slopes. Common grassland species include wild oat, rye, soft chess, fescue and other annual and perennial grasses and some forbs. Grassl and areas on the Horse Ranch property are used for horse grazing.
Mixed evergreen woodland covers approximately half of the undeveloped area in the San Juan Hills planning area. It forms a dense, close-canopied forest and is located primarily in the draws of north-facing canyon slopes.
Common tree species include coast live oak, California bay, and buckeye. Less frequent species include toyon and other shrubby evergreen species. Extensive stands of mixed evergreen woodland occur on the steep east-facing slope of San Juan Canyon. Mixed evergreen woodland, together with riparian woodland, forms an important physical connection to the open space of Sugarloaf Mountain north of the planning area.
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Chaparra 1 covers about 25 percent of the San Juan Hi 11 s planning area and, 1 i ke the annua 1 grass land that it is sometimes mixed with, occurs on drier southwest-facing slopes. Chamise and coyote bush dominate the chaparral areas, with poison oak and toyon occurring less frequently. These species form impenetrable stands from four to eight feet high. Chaparral and annual· grassland extend continuously from the wide slope north of the Skymont area to Sugarloaf Mountain.
Riparian woodland covers substantially less area than the other vegetation types, comprising less than one percent of the total vegetation in the San Juan Hills planning area. Riparian woodland stretches along the entire 1 ength of East Laure 1 Creek from its western reaches near the Horse Ranch property to the junction of East laurel Creek Road and Haskins Drive at the eastern boundary of the planning area. The riparian zone boundary extends from approximately two to twenty-five feet away from the banks of Laurel Creek forming a tot a 1 riparian zone width of between four and fifty feet. In genera 1, the riparian zone width decreases as e 1 evat ion increases and is narrowest at the head of laurel Creek Canyon.
Willow, a dominant riparian species, forms dense thickets from five to ten feet in height in the upper parts of Laurel Creek Canyon. As Laurel Creek Canyon narrows near its junction with San Juan Canyon the vegetation assumes more woodland characteristics. The willows have a tree-like form and bay, oak and buckeye form a dense canopy above shrubby and herbaceous riparian species.
Riparian shrub species include willow, coffeeberry., rose, blue elderberry, gooseberry, ninebark and poison oak. Common understory riparian species present in the planning area include woody species such as honeysuckle and thimbleberry; ferns, such as golden-backed fern and sword fern; and herbaceous species including hemlock, vetch, stream orchid; and grasses including rushes, sedges and a variety of annual and perennial grasses. Downstream from the junction of the two canyons, the riparian corridor is wide and oak and bay trees reach heights of nearly 50 feet. A few equally large deciduous oaks are also present in this area.
A small intermittent tributary to East Laurel Creek runs along lower San Juan Boulevard north of its intersection with Marburger Avenue. The riparian veg et at ion a 1 ong this drainage is patchy and 1 ess we 11 deve 1 oped than the riparian vegetation in East Laurel Creek and consists mostly of thimbleberry and a few ferns. Oak and bay trees line portions of the tributary except where residential development and/or non-native species occur.
Non-native species planted in or around existing residential development in the planning area include Monterey pine, eucalyptus, acacia, pyracantha and 876
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cotoneaster. Some introduced species have naturalized and become established in the planning area including periwinkle, ivy and pampas grass.
No known State or Federa 11 y 1 i sted rare or endangered species were observed during a field reconnaissance conducted on December 4, 1986, nor have any such species been previously observed in the San Juan Hills area (California Natural Diversity Data Base, 1986).
Wildlife. · The natural features of the San Juan Hills, especially Laurel Creek Canyon, coupled with the close proximity of the large open space areas on Sugarloaf Mountain provide habitat for a relatively abundant and diverse wildlife population. Wildlife habitat is related to vegetation type and is based on wi 1 dl if e requirements for food, cover and nesting, den sites or roosting sites. In general, bird species associate with one vegetation type while mammals move between more than one vegetation type. The following discussion of wildlife species in the planning area is presented according to the habitat types present. Appendix C presents a 1 i st of potent i a 1 and observed wildlife species in the planning area.
The mixed evergreen woodland in the planning area supports a diversity of bird species. Birds which feed on insects at the canopy level include plain titmouse, chestnut-backed chickadee, ash-throated flycatcher, bushtit, Hutton's vireo, solitary vireo and yellow-rumped warbler. The oak and bay trees al so provide an abundant direct food source in the form of acorns and bay nuts for seed-eating birds, western gray squirrels and dusky-footed woodrats. Additional bird species found in the evergreen forest, most of which forage at or near the ground 1 eve 1 , inc 1 ude Ca 1 i forn i a thrasher, fox sparrow, hermit thrush, brown towhee and orange-crowned warbler.
The mixed evergreen woodland also includes a variety of dead trees (snags), or portions of dead trees which are an important habitat component for many birds which excavate nesting cavities in the dead trees. Acorn woodpecker, Nutt a 11 's · woodpecker and common flicker are the primary cavity nesters. Birds that use old nesting cavities include American kestrel, ashthroated flycatcher, chestnut-backed chickadee, brown creeper and whitebreasted nuthatch. Red-tailed hawk, great horned owl and a variety of smaller perching birds use dead trees and limbs for perching and roosting sites.
Small to mid-sized mammals including mice, skunks and raccoons use fallen dead trees for den sites. Dusky-footed woodrats utilize sticks to make nests.
Amphibians and reptiles that occur in the mixed evergreen woodland include California slender salamanders, yellow-eyed salamanders, arboreal salamander, western skunk and northern alligator lizard. 877
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The annual grasslands in the San Juan Hills planning area and on adjacent Sugarloaf Mountain support small rodents including Botta's pocket gopher, California ground squirrel, western harvest mouse and California vole. These rodents feed on young grasses and forbs and bui 1 d subterranean runways and dens in the annual grassland. Many animals use grassland as a hunting area preying on rodents, fledgling birds and lizards. Predators include red-tailed hawk, American kestrel, great horned owl, Pacific gopher snake, western rattlesnake, coyote, gray fox and striped skunk. Birds forage for grass seeds, insects and young shoots in annual grassland and include western meadowlark, western bluebird, savanna sparrow, white-crowned sparrow, house finch and California quail.
The chaparral in the planning area supports many of the same species found in the annual grassland. Chaparral provides more cover then grassland and wildlife will often feed in grassland and seek cover or bedding sites in adjacent dense chaparral brush. Scrub jay, brown towhee, dark-eyed junco, golden-crowned sparrow, deer, coyote and gray fox use chaparral and annual grassland for cover and bedding sites. Species which associate with chaparral for both cover and food value include brush rabbit, brush mouse, California thrasher, wrentit, Anna's hummingbird and rufous-sided towhee.
Al though riparian woodland covers much less area than the three other vegetation types in the planning area, it supports the greatest abundance and diversity of wildlife. The presence of a variety of food sources in riparian woodland areas contributes to the diversity of bi rd species found in Laure 1 Creek Canyon. Willows and trees support large insect populations at the tree canopy level, which in turn provide a food source for the same insect-eating birds that occur in the mixed evergreen woodland. At the tree canopy level, oak and bay trees support insect populations and provide a direct food source in the form of oak acorns and bay nuts to birds such as acorn woodpecker, Nuttall's woodpecker, western flycatcher, and scrub jay. The trees and shrubs also provide necessary nesting and roosting sites for all of the above birds.
At the shrub level, coffeeberry, rose, poison oak and elderberry provide berries to fruit-eating birds including purple finch, varied thrush, hermit Thrush, robin and some of the insect-eating birds that supplement their diet with fruits. Ground foraging species present in the riparian woodland include golden-crowned sparrow, song sparrow, and fox sparrow.
Mammals closely associated with the riparian areas include opossum, striped skunk, raccoon, ornate shrew and mole. These animals all feed to some extent on the variety of invertebrates living in the moist soil and debris of j the riparian areas. Larger mammals, including black-tailed deer, coyote and gray fox use the riparian areas as travel corridors and water sources. Laurel Creek Canyon is an important trave 1 corridor connecting San Juan Hi 11 s to 878
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Sugarloaf Mountain. Deer move onto Sugarloaf Mountain in 1 ate winter and spring to browse on the young grasses, forbs and shrub shoots. During a field reconnaissance on December 4, 1986, raccoon, coyote, deer, California slender salamander and numerous songbirds were observed in Laurel Creek Canyon.
Opossum, raccoon, skunk and coyote may also use the culverted sections of East Laurel Creek for bedding and nesting sites during the dry season.
Reptiles and amphibians are also found in the riparian woodland.
Amphibians, including California slender salamander and yellow-eyed salamander, rely on leaf litter, decaying logs and other forest floor debris for food, cover and nesting sites. Rept i 1 es that feed on insects and other invertebrates in the riparian woodland areas include ring-necked snake and terrestrial garter snake. Pacific gopher snake, kingsnake, racer, and western rattlesnake live in riparian areas and prey on small mammals and amphibians.
An important habitat type in the San Juan Hills planning area occurs where one vegetation type abuts or gradually merges with another vegetation type. These areas, called ecotones or edge habitat, are extensively used by species that forage or hunt in one vegetation type and seek cover or nesting sites in the adjacent vegetation type. Birds and large mammals associated with riparian woodland use the adjoining ecotone areas. In the planning area, an ecotone exists a 1 ong the entire 1 ength of the riparian woodland edge of East Laurel Creek.
Residential areas also provide habitat for wildlife, especially where native vegetation remains or where suitable landscape vegetation has been planted. Birds use trees and shrubs for foraging and cover. Non-native trees and shrubs that provide habitat for birds include pine, eucalyptus, pyracantha and cotoneaster. Deer often take advantage of home gardens to supplement their regular diet and scavenging animals, such as skunks, raccoons, scrub jay and Stellar's jay also frequent residential areas.
No known rare, endangered or sensitive species were seen during the field survey, nor have any such species been previously recorded or observed in the San Juan Hills area (California Natural Diversity Data Base, 1985).
Potential Impacts
The San Juan Hills Area Plan includes policies which would protect vegetation, streams and creeks in the planning area and encourage the establishment of open space areas. The Natural Resources policies of the Area Plan protect vegetation by requiring that development minimize vegetation removal, protect and restore vegetation which stabilizes soils and reduces surface water runoff, protect historic and scenic trees, and provide 879
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revegetation of all significant tree cover. Streams and creeks are protected by policies requiring that development and roads are set back from riparian corridors, and by preventing road alignments that cross creekbeds. The Area Plan encourages clustered development to maximize open space and offers public assistance to landowners to help find ways of managing and permanently preserving private open space that is not suitable for development.
The Area Pl an emphasizes the need to protect the natura 1 resources in Laurel Creek Canyon and open space on Sugarloaf Mountain. Area Plan policies recommend creation of an open space buffer between - deve 1 opment on vacant parcels in the San Juan Hills and Sugarloaf Mountain and creation of a continuous greenbelt of publicly-owned open space. The density transfer, lot merger, and resubdivision programs of the Area Plan are intended to minimize development in Laurel Creek Canyon in order to preserve resources and open space in the area.
Although the Area Plan policies would help to protect the natural resources of-the San Juan Hills and maximize the amount of private and public open space in the area, future development in the area would still have an impact on vegetation and wildlife resources. - The extent of impacts on vegetation and wildlife would be related to the location and extent of future development.
The proposed density transfer, 1 ot merger and resubd i vision programs would in large part determine where future development would be located.
These programs are intended to consolidate development in areas which are not geologically hazardous and which would not degrade natural resources. Figure 7 depicts a potential future development pattern for the planning area based on the Area Plan policies. For development in Laurel Creek Canyon, the Area Plan designates three "receiver" sites which would be eligible to purchase development rights from other property owners in the Laurel Creek Canyon area.
The sites comprise almost 20 acres, located on the uppermost elevations of the Laurel Creek Canyon subarea. The Horse Ranch property, and two parce 1 s adjacent to Bi shop Road on the Skymont Plateau are designated as receiver sites.
The receiver sites are primarily vegetated with annual grasses and chaparral species. Full development of the 68 residential units permitted in this area by the Area Plan would result in the removal of grassland, chaparral, and some eucalyptus trees. If the maximum amount of development were to occur on the receiver sites, vegetation remova 1 at the Bi shop Road sites would result in the loss of approximately five acres of annual grassland and one acre of chaparral. Vegetation remova 1 at the Horse Ranch property would result in the loss of approximately four acres of annual grassland, a 880
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group of eucalyptus trees and minimal amounts of chaparral and mixed evergreen woodland. The grassland and chaparral vegetation at the Horse Ranch property, however, is already disturbed due to horse grazing. Grassland and chaparral are generally more abundant and less sensitive to disturbances than are other vegetation and habitat types in the planning area. Removal of grassland from future development in the San Juan Hills would not be expected to significantly impact the overall biological diversity or productivity of the planning area.
If fully implemented, the density transfer program would result in the preservation of the sensitive riparian woodland vegetation in Laure 1 Creek Canyon. If all development rights are transferred, the "sending" sites in the Canyon would be permanently preserved as open space. The associated vegetation and wildlife values of the riparian woodland in these areas would be preserved as well.
There are some areas in Laurel Creek Canyon that are not. designated sender sites in the Area Plan. Development of these areas, which either abut or are located within riparian woodland would result in a loss of riparian woodland and associated habitat types. Similarly, non-transference of deve 1 opment rights in the riparian areas of Laurel Creek Canyon would al so result in a reduction of riparian woodland and habitat. Potential storm drainage improvements including rechannelization or culverting of East Laurel Creek would reduce riparian woodland and habitat as well. Private development within a riparian corridor would require a streambed alteration agreement under Section 1603 of the California Fish and Game Code prior to development, while public development would require a streambed alteration agreement under Section 1601 of the California Fish and Game Code.
Relatively minor amounts of mixed evergreen woodland and chaparral would be lost if development occurred in the lower elevations of the Bartlett subarea that ,xtend into Laurel Creek Canyon. Development here would be less det ri men ta 1 to vegetation and wi 1 dli f e s i nee mixed evergreen woodland and chaparral are more abundant and 1 ess sensitive than riparian woodland or ecotone areas adjoining riparian woodland.
Residential development often attracts wildlife including birds, deer, skunk and racoon due to the presence of gardens, 1 andscapi ng and refuse disposal. Deer can enter and browse suburban gardens wherever development is located in or adjacent to a wildland setting, as would occur in the San Juan Hills. Deer regularly enter such areas and often incorporate them into their home range. Any ornamental species planted for landscaping may offer higher quality food than currently exists on the site. As such, problems with deer browsing would be expected in gardens without fencing. Domestic dogs and cats 881
70 can sometimes depredate suburban wildlife.
Mitigation Measures
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In addition to the mitigating policies of the proposed San Juan Hills Area Pl an, the fo 11 owing measures are recommended to minimize imp acts on vegetation and wildlife in the San Juan Hills due to development in the area:
1. The loss of annual grassland, chaparral, eucalyptus and mixed evergreen woodland on the receiver sites would be mitigated through the creation of permanent open space on the sender sites.
2. As required by the State Fish and Game Code, a 1601 streambed alteration agreement must be negotiated prior to any deve 1 opment undertaken by a public entity, such as the City of Belmont, and a 1603 agreement must be negotiated prior to any private development, which would result in alteration of East Laurel Creek or its associated riparian vegetation.
3. Native plant species should be used for revegetation and landscaping purposes in areas where residential development occurs in order to provide habitat for and minimize impacts on suburban wildlife.
Native species valuable to wildlife and suitable for landscaping include such species as California black walnut (Juglans hindsii), coast silk tassel (Garrya elliptica), coffeeberry (Rhamnus californica) and ceanothus.
4. If vegetation is cleared, manual removal of undesirable vegetation, rather then herbicide treatment should be instituted.
5. To preserve wildlife habitat in East Laurel Creek, dead and down debris should be maintained unless it poses the potential for fire or flood hazards.
6. Equipment operation should be avoided within the dripl ine of all trees to be preserved. Once equipment operation is comp 1 eted, disturbed areas within driplines should be lightly spaded by hand to loosen surface soil. Leaf 1 itter and understory vegetation, which would act as a buffer against compaction, should be retained in areas of equipment operation.
7. Irrigation and sprinkler systems, as we 11 as drainage from residential rooflines, should be diverted to avoid dripline areas. 882
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VISUAL QUALITY
Setting
The San Juan Hills area consists of a primarily residential landscape situated on three plateaus (see Figure 3). In between these plateaus and at the northern periphery of the planning area, there are large tracts of undeve 1 oped 1 and. The topography of the San Juan Hi 11 s, a 1 ong with the relatively large open space areas provide striking views both from and to the planning area. Figure 4 illustrates the pattern of development and open space in the project area.
From locations on the upper elevations and hillsides of the plateaus, wide vistas of the open space areas in Laurel Creek Canyon, San Juan Canyon and Sugarloaf Mountain are available, with views of San Francisco Bay in the distance. The locations of the major features in the planning area are shown in Figure 3. Figure 14 shows a view of the upper reaches of Laure 1 Creek Canyon with Sugarloaf Mountain and San Francisco Bay in the distance.
From locations outside of the planning area, much of the San Juan Hills is visible. In particular, views from State Route 92 and Ralston Avenue, two major regional scenic routes, encompass much of the planning area. From State Route 92, deve 1 opment in a 11 three of the planning area neighborhoods is visible, and the wooded north- and west-facing hillsides accentuate the topography of the San Juan Hills. From Ralston Avenue, close range views of development in the planning area are afforded as well as more distant views across the planning area. Figure 15 illustrates the view across the Horse Ranch property from a designated vista point on Ralston Avenue.
Although almost two thirds of the planning area is developed, the undeveloped portions of the area, particularly in Laurel Creek Canyon, convey an impression of a large open space area that is completely secluded and protected from surrounding development. This rural, isolated character is due to the steep topography and heavy vegetative cover of the planning area. The riparian woodland in Laure 1 Creek Canyon and the dense stands of trees and open chaparral and grasslands on surrounding hillsides contribute to the scenic appeal of the planning area. The open space areas within the planning area are used by local residents for passive recreational activities, such as walking and jogging.
The qua 1 i ty of the natura 1 views in the- San Juan Hi 11 s is disturbed in many locations by residential development on the hillsides. Residences developed on very steep hillsides are often fully exposed and can appear massive from opposite hillsides. In addition, large cuts in the slopes and 883
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retaining walls detract from the visual appeal of hillside development. Under existing regulations, very large houses are permitted on some parcels. Such houses often appear out of scale with nearby residences. Figure 16 presents two pictures which illustrate the potential scale and visual impact problems associated with building on the steep hillsides of the planning area.
Potential Impacts
Future deve 1 opment under the proposed San Juan Hi 11 s Area Pl an would permit a maximum of 372 units to be constructed in the project area. Table 1 indicates a potential number of units by subarea and Figure 7 illustrates a potential pattern of future development. Development permitted under the Area Plan would be approximately 38 percent less than that which could occur under maximum buildout of the existing General Plan. This lesser level of development would result in a lesser amount of visual impacts. In addition, the Area Plan presents the following goals to preserve the visual quality of the San Juan Hills:
o Site and design new development to protect public views, particularly from Ralston Avenue to Laurel Creek Canyon toward Stigarloaf Mountain and San Francisco Bay.
o Site and design structures to maximize view preservation. o Cluster development wherever possible on the most developable portion of a site, leaving the maximum portion of the site in its natural state.
o Minimize the buildout of existing vacant subdivided lots in those areas where buildout would be geologically hazardous, require major road extensions and improvements and degrade natural resources and views.
o Ensure that new structures are designed to protect the vi sua 1 and natural resource quality.of the hillsides.
As described in the Land Use section of this EIR, the quantity, density and distribution of development under the Area Plan differs from the development pattern promoted by the existing General Plan. The Area Plan restricts the overall amount of development in the area by confining it to geologically stable areas, and promoting a program of lot merging, resubdivision and density transfer. Overall, the Area Plan would consolidate the spatial dispersement of development, thereby reducing potential visual impacts. Nevertheless, any additional development in the area would impair 886
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the visual quality of the San Juan Hills as viewed from certain areas. The potential visual impacts due to development relate primarily to the location and the structural design of the residential units.
Location of Future Development. The most significant potential visual impacts due to development in the planning area would occur at the three designated receiver sites in the Laurel Creek Canyon subarea. These sites are 1 ocated in the upper reaches of the Laurel Creek Canyon on the Horse Ranch property and to the north and west of the Baptist Church in the Skymont neighborhood. · All three of the receiver sites are presently covered predominantly by grassland with scattered trees and shrubs. The Horse Ranch site is highly visible from locations on Ralston Avenue {see Figure 15) and from the Plateau and Skymont neighborhoods. The receiver sites near the Baptist Church are highly visible from an adjacent residential development and State Route 92 to the west. Both the Horse Ranch and the Baptist Church sites are visible from Sugarloaf Mountain to the north. Figures 17 and 18 present photographs of the Horse Ranch and the Baptist Church sites.
Under the Area Plan, approximately 68 residential units could be developed at these sites. This development would be at a lower gross densities than existing development in the vicinity but may be developed as attached dwelling units. As described above, it would be highly visible from vantage points both within and outside of the planning area.
Because of the steep topography of the area, other development in the San Juan Hills would be visible primarily from locations within the planning area.
As is the case with existing development, future development on the hillsides would be particularly visible. Although Area Plan policies would minimize the extent of hillside development, almost all future development other than small areas of infill and development at the receiver sites would be located on the hillsides.
Overall, the potential development of 372 additional residential units, both as infill and as extensions of existing neighborhoods, would contribute to a more urban character of the area and would result in the remova 1 of a substantial amount of the natural vegetation and open space which add to the currently high visual quality of the San Juan Hills.
Site Development Standards. In the past, there has been a lack of appropriate site development standards in the San Juan Hills area which has served to exacerbate the visual impacts associated with hillside development. 888
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The zoning ordinance was recently amended to provide for measurement of the entire structure height in establishing height 1 imits. However, development standards which minimize the visual impact of height, such as break up of vertical surfaces, and terracing and encouraging roof lines that are parallel to the slope. There are no grading design standards which establish grading practices that minimize changes from natural grade and there are no standards governing revegetation of sites after development.
The proposed Area Plan includes policies to ensure that future residential development is compatible in scale with nearby uses and to regulate the visual impact of development on hillsides. Under the Area Plan, a slope intensity ordinance would establish Floor Area Ratios which more effectively establish house sizes which are visually compatible with the size and slope of the lot on which they are located and the size of the majority of existing houses in the area. (Revised floor area ratio standards developed by the San Juan Committee for consideration in developing the implementing ordinances are presented in Appendix 8.) Site development standards would be established to ensure that structures are designed to -conform to the topography of their site. This would be accomplished in part by limiting the permitted height of structures to reflect the slope of the lot and by restricting the bulk of structures in hillside locations. In addition, the design of structures would be controlled so that large vertical and roof surfaces are broken up and terracing of homes is encouraged.
Preservation of the natural integrity of building sites is also promoted by the Area Pl an which ca 11 s for the es tab 1 i shment of grading standards to minimize grading and vegetation removal and to require revegetation during and after site development.
Mitigation Measures
In addition to adoption of the mitigating policies of the Area Plan discussed above, the following measures are recommended to offset potential adverse visual impacts of future development:
1. Development on the Horse Ranch property and the two parcels adjacent to the Baptist Church should be sited and designed to minimize visual impacts. The scale of the development should be compatible with existing residential uses in the area. Material used should be selected to promote the visual blending of the structures into the landscape. The siting of buildings and landscaping should be sensitive to existing view corridors from Ralston Avenue and surrounding residential areas.
891
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2. The implementing ordinances for the Area Plan should include a policy requiring that revegetation efforts utilize native plant species which should be established in patterns which are harmonious with existing vegetation in the area.
3. Design review approval should be required for new single-family residences in the San Juan Hills area and a case-by-case determination should be conducted to ensure effective application of visual standards.
892
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TRAFFIC AND CIRCULATION
Setting
Roadways. Access to the San Juan Hi 11 s planning area is provided by a network of highways and surface streets, as shown in Figure 19. Regional and sub-regional access to the project area is provided by State Route 92, Interstate 280, and Alameda De Las Pulgas. State Route 92 has two lanes in each direction and extends east to the cities of San Mateo and Hayward (with connections to other Bay Area freeways) and west to an interchange with 1-280 and the City of Half Moon Bay. State Route 92 is a two-lane roadway between 1-280 and Half Moon Bay. Interstate 280 is an eight-lane freeway which extends from San Francisco to San Jose. Alameda De Las Pulgas is a two-lane roadway which extends north into San Mateo and south to San Carlos. It intersects both Ralston Avenue and Cipriani Boulevard to the east of the planning area.
Local access in the planning area is provided by Ralston Avenue, Cipriani Boulevard, Christian Drive, San Juan Boulevard, Belmont Canyon Road, and Hi 11 crest Ori ve. Ra 1 ston Avenue is a four-1 ane, major roadway running in a general east-west direction adjacent to the southern planning area boundary.
It extends westerly and northerly as a four-1 ane roadway to an interchange with State Route 92, and easterly as a two- to four-lane roadway to intersections with Alameda De Las Pulgas, El Camino Real, and an interchange with U.S. Highway 101. Residential and open space areas line Ralston Avenue near the planning area. On-street parking is not allowed on either side of the street. Curbs and gutters are provided on both sides of the street.
Left-turn lanes are provided on the approaches to all major intersections and all major intersections and interchanges are signal controlled. The posted speed limit is 35 miles per hour, although observed speeds ranged as high as 55 miles per hour. Signalized intersections on Ralston Avenue adjacent to the planning area include Christian Drive, Lassen Drive, the central access point of Belmont Canyon Road, Davis Drive, and Cipriani Boulevard. All other side street approaches along the planning area boundary are stop-sign controlled.
There was little pedestrian and bicycle activity observe� along Ralston Avenue during the field observation for this EIR. Observed traffic safety concerns include the restricted sight distances for vehicles turning right from the unsignalized Belmont Canyon Road approaches to Ralston Avenue and the lack of right-turn deceleration lanes on the westbound Ralston Avenue approaches to the central access Belmont Canyon Road and Christian Drive.
Cipriani Boulevard is a two-lane roadway with numerous curves running in a general north-south direction. It extends northerly to a connection with Alameda De Las Pulgas, and southerly to a connection with Ralston Avenue. 893
NORTH
I 000 Feet ¾ Mile
lsa
82 -
I Mole
FIGURE 19
''
'%�
' ',t' " �,,.,,: \ SOURCE. , . .. .• _ .•.
LOCAL ROAD NETWORK
894
83 lsa
Residential units line Cipriani Boulevard. Left-turn lanes are not provided on the approaches to any intersection along Cipriani Boulevard with the exception of Ralston Avenue. The observed vehicle speeds on Cipriani Boulevard ranged from 20 to 35 mil es per hour. On-street parking is not possible on either side of the street in most locations. Cipriani Boulevard has a general uphill gradient south to north. It is signal controlled at Ralston Avenue and stop-sign controlled (four-way) at Ponce Avenue, Buena Vista Avenue, and Newlands Avenue. All other side street approaches are stopsign controlled. There was little pedestrian or bicycle activity observed along the street during field observation. An observed traffic safety concern is the occas i ona 1 backup of northbound vehicles at the San Juan Baul evard intersection as they attempt left turns, or less frequently, as they attempt to cross Ralston Avenue. Vehicles turning left from Cipriani Boulevard must stop while waiting for southbound traffic to clear and thus block the single northbound lane. Through traffic is usually unable to pull around the turning vehicle due to the narrow width of the northbound travel lane.
San Juan Boulevard is a two-lane roadway running in a general east-west direction through the eastern portion of the planning area. It extends easterly to a connection with Cipriani Boulevard near Ralston Avenue, and westerly and northerly to an intersection with East Laurel Creek Road.
Residential units 1 ine most of San Juan Boulevard. Left-turn lanes are not provided on approaches to any intersection on San Juan Boulevard. The observed speeds on San Juan Baul evard ranged from 20 to 40 mi 1 es per hour.
On-street parking is allowed on both sides of the street in most locations except on the insides of curves. Curbs and gutters are provided on both sides of the street. San Juan Boulevard has a general downhill gradient east to west. It is stop-sign controlled at Cipriani Boulevard and Monte Cresta Drive (three-way stop). There was some pedestrian, bicycle, and skateboard activity observed along the street during field observation. Observed traffic safety concerns include inadequate roadway width for two-way vehicle flow when vehicles are parked on both sides of the street, unsafe driving speeds, and dangerous riding patterns of some skate boarders. In addition, if cars are parked on one side of the street, vehicles traveling on the same side of the street must pull around parked vehicles and drive partially in the opposite direction travel 1 ane, thus posing a hazard to pedestrians and bike riders.
Residents have complained that if parking is prohibited along one side of the street, vehicle speeds would increase to unacceptable levels. In addition, most residents do not want to give up on-street parking adjacent to their homes.
Christian Drive is a two-lane roadway running in a general north-south direction. It extends northerly from a signalized intersection with Ralston Avenue into the westernmost Skymont section of the San Juan Hi 11 s planning 895
84 lsa
area. Residential uni ts lines most of Christi an Drive. Left-turn lanes are not provided on the approaches to any roadway from Christi an Drive. The observed speed limit ranged from 25 to 35 miles per hour. On-street parking is allowed on both sides of the street. Curbs and gutters are also provided on both sides of the street.' There was a minor amount of pedestrian and bicycle activity observed along the street during field observation. An observed traffic safety concern is the close proximity of the Christian Drive/Green Court intersection with the Christian Drive/Ralston Avenue intersection ( about 30 feet apart). Vehicles turning from Green Court onto Christian Drive create safety problems for those vehicles turning from Ralston Avenue onto Christian Drive. This problem is currently insignificant due to the low volume of traffic using Green Court.
Belmont Canyon Road is a curving two-lane roadway within the San Juan Hills planning area which runs in a general east-west direction just north of Ralston Avenue. Residential units line most of Belmont Canyon Road. Leftturn 1 anes are not provided on approaches to any intersection a 1 ong Belmont Canyon Road. Observed vehicle speeds ranged from 15 to 25 mil es per hour.
On-street parking is allowed on both sides of the street in most locations.
Curbs and gutters are also provided on both sides of the street in many locations. It is stop-sign controlled at Ralston Avenue at its easterly and westerly end, and is signal controlled at Ralston Avenue at a midpoint location. There was some pedestrian and bicycle activity observed along the street during field observation. Traffic safety concerns re late to the inadequate roadway width for two-way vehicle flow when vehicles are parked on both sides of the street and the subsequent diversion of vehicles into the opposing lane of travel as they drive around parked vehicles.
In general, all other paved roadways serving the San Juan Hills planning area are two-lanes wide with on-street parking allowed. Two-way traffic flow, however, is impossible with vehicles parked on both sides of the street. Some roads have steep gradients and sharp curves. Stop signs are lacking on approaches to many intersections; however, most vehicles either slow down or stop at these intersections. Sight distances are restricted on many internal area intersection approaches due to landscaping, natural foliage, and/or differences in roadway gradients.
Traffic Volumes. Existing p.m. peak hour volumes on local roads in the planning area vicinity are shown in Figure 20. Volumes on Ralston Boulevard are heavy and range from 2,500 to 2,700 vehicles per hour adjacent to the San Juan Hills planning area. Volumes on Cipriani Boulevard are moderately heavy at 970 vehicles per hour. Vo 1 umes on Christi an Drive, Belmont Canyon Road, and San Juan Boulevard are lighter, and range from 175 vehicles per hour on 896
LEGEND --�---.. --•--· _,
XX EXISTING TRAFFIC VOLUMES (FALL 1986)
{XX) ADDITIONAL TRAFFIC DUE TO BUILDOUT UNDER An£A PLAN XX ADDITIONAL TRAFFIC DUE TO CUMULAlIVE BUILDOUT
g
�-
�-
00 -:,
�
-::
1 25
70)
1585
(115)-
70 --
�-
�
"'
�
1540
(65) - 70
SOURCE: Goodrich Traffic Group.
�
'i
�
1550-
(45)
65 280
l
1305
(55
65 )-
(30)
135
870
{25) _....
65 1710
(5)
150
1700�-, (IO) 100"
t � -10 "to
�lO<ll ��
960
(1
0i
215 ) 93
- (5
�145
740
(130)/
15 �
NORTH
1,000
0 Feet
I I
j Mile
I
lsa FIGURE 20 EXISTING AND FUTURE TRAFFIC VOLUMES
OJ u,.
897
86 lsa
Christian Drive to 210 vehicles per hour on San Juan Boulevard, and 235 vehicles per hour on the central section of Belmont Canyon Road.
Intersection Operation. Intersections are almost always the critical factor in determining the traffic handling capacity of any circulation system.
Intersection traffic operation is measured by a scale called Level of Service (LOS). The scale ranges from LOS "A", which indicates uncongested flow and the least delay on intersection approaches, down to LOS "F", which indicates operation over theoretical capacity with significant congestion and delay for drivers. Most urban 1 ocat ions use LOS "D" operation as the poorest level acceptable, while smaller, rural areas use LOS "C" as their minimum standard.
For this study, a capacity analysis was conducted for the Ralston Avenue signalized intersections with Christian Drive, Belmont Canyon Road, Cipriani Boulevard, Alameda De Las Pulgas, and El Camino Real (see Table 4). The three intersections adjacent to the planning area are now operating at good levels of service of A or B during p.m. peak hour traffic conditions. Although the Ralston Avenue/Cipriani Boulevard intersection is operating at a good peak hour level of service of B, a significant safety problem is beginning to occur due to traffic in the eastbound (downhill) Ralston Avenue left-turn lane occasionally backing up and extending into the high speed through travel lane.
The Alameda De Las Pulgas intersection with Ralston Avenue is now experiencing significant congestion on two of its four approaches and is operating at LOS D during the p.m. peak hour time period. The lack of separate left-turn phases for traffic turning from Alameda De Las Pulgas to Ralston Avenue createf some of this congestion and causes many near accidents at this intersection. The Ralston Avenue/El Camino Real intersection is also operating close to capacity (LOSE) during the same time period with significant congestion on several intersection approaches. Traffic flow on Ralston Avenue through the El Camino Real intersection is further disrupted due to train movements across the eastern leg of the intersection, which frequently occur during the evening peak traffic period. Appendix D presents capacity work sheets for each intersection.
Transit Service. San Mateo County Transit routes 458 and 40R provide transit service to the planning area along Ralston Avenue. Route 40E provides service along Cipriani Boulevard. Route 458 also travels along Christian Drive and Bishop Road in the Skymont section of the San Juan Hills planning area.
!According to the City of Belmont Department of Public Services, a contract was awarded in March 1987 to add protected left turn lanes on Alameda De Las Pulgas at the Ralston Avenue intersection.
898
Intersection
Ralston/Christian
Ralston/Belmont Canyon
(central access)
Ralston/Cipriani
Ralston/Alameda De Las
Pulgas
Ralston/El Camino Real
*Level of Service
A
B
C
D
E
F
87 TABLE 4
INTERSECTION SERVICE LEVELS*
{PM Peak Hour)
Existing
V/C LOS
.53 A
.47 A
.65 B
.86 D
.97 E
V/C Ratio
<0.60
0.61-0.70
0.71-0.80
Existing+
Project
V/C LOS
.56 A
.50 A
.70 B/C
.89 D
.98 E
Conditions
Free flowing
Stable fl ow
Restricted fl ow
lsa
Existing+
Project+
Cumulative
V/C LOS
.58 A
.58 A
.75 C
.92 E
1.09 F
0.81-0.90 Nearing unstable flow
0. 91-1. 00 Capacity flow
>1.00 Demand exceeds capacity
Source: Goodrich Traffic Group
899
88 lsa
Planned Improvements. Local jurisdictions in the planning area vicinity are not planning any major circulation system improvements in the immediate future. Likely, minor improvements include the replacement of controllers on several signalized intersections along Ralston Avenue {Adel Nepomuceno, City Engineer, personal communication).
Potential Impacts
The proposed Area Pl an would permit 1 ess development in the San Juan Hills than could occur under the existing General Plan. Therefore, traffic generated by future development in the planning area would be less under the Area Pl an than under the Genera 1 Plan. Potent i a 1 impacts due to traffic levels which would result from Area Plan buildout are discussed below. Area Plan policies relating to road extensions, hillside road standards and maintenance responsibilities are discussed in the Public Services and Utilities section of this EIR.
Trip Generation. Potential buildout of the San Juan Hills planning area under the proposed Area Plan, including infill of existing developed sections, would generate about 3,720 new daily two-way trips with about 250 new inbound and 125 new outbound p.m. peak hour trips. Approximately 32 percent of the tot a 1 trip generation ( 120 peak hour trips) would be associated with new development in the Skymont area, while 24 percent (90 peak hour trips) would be associated with new development in the Plateau area, and 44 percent {165 peak hour trips) would be associated with the development of the Cipriani area.
Trip Distribution. Potential p.m. peak hour traffic due to buildout of the planning area was distributed to the local roadway system based on existing area traffic circulation patterns and potential changes in patterns due to new internal roadway connections. The roadway connections considered in the trip distribution include the connection of the Cipriani area to the Plateau area vi a a paved Marburger Road { see Figure 7}. Other potent i a 1 roadway connections were not considered in this analysis because extreme geologic hazards would probably preclude their development. Figure 20 shows additional planning area buildout traffic distributions within the local roadway network. The volumes shown in Figure 20 reflect redistribution of existing volumes due to new internal roadway connections in the San Juan Hills planning area. The assumed distribution of traffic in the San Juan Hills area is shown below:
900
89 PROJECT TRAFFIC DISTRIBUTION
(PM Peak Hour)
To/from the north
via Cipriani Boulevard
To/from the east
via Ralston Avenue
To/from the west
via Ralston Avenue
Local Area
15%
35%
45%
5%
100%
lsa
Roadway and Intersection Impacts. Traffic due to additional buildout of the planning area would increase existing p.m. peak hour roadway volumes by the amounts shown in Table 5.
Net traffic increases would be s i gni fi cant on Ra 1 ston Avenue east of Cipriani Boulevard and west of Christian Drive with p.m. peak hour volume increases of 125 and 155 vehicles per hour (vph) respectively, and on Christian Drive, Belmont Canyon Road, and San Juan Boulevard in the vicinity of Ralston Avenue with p.m. peak hour volume increases of 105, 70, and 105 vph respectively. However, all existing roadways have available physical capacity to accommodate the increased traffic volumes due to buildout under the Area Pl an.
Buildout traffic would not produce significant peak hour impacts at any of the analyzed intersections (see Table 4). Buildout traffic would use three percent of tot a 1 existing capacity at the Ra 1 ston Avenue/Christi an Ori ve intersection; three percent of total existing capacity at the Ralston Avenue/Belmont Canyon Road intersection; five percent of total existing capacity at the Ralston Avenue/Cipriani Boulevard intersection; three percent of total existing capacity at the Ralston Avenue/Alameda De Las Pulgas intersection; and one percent of total existing capacity at the Ralston Avenue/El Camino Real intersection.
At the Ralston Avenue/Cipriani Boulevard intersection, traffic resulting from bu il dout under the Area Pl an would result in a LOS B/C. Intersection p.m. peak hour LOS designations would remain the same at all other analyzed locations after the addition of buildout traffic under the Area Plan. 901
1. 2.
3. 4.
5. 6.
7. 8.
9. 10.
11. 12.
13. 14.
15. 16.
90 TABLE 5
ROADWAY IMPACTS DUE TO PLANNING
AREA BUILDOUT TRAFFIC
Roadway
Ralston Avenue
(east of Route 24 Freeway)
Ralston Avenue
(east of Christian Drive)
Ralston Avenue
(west of Cipriani Boulevard)
Ralston Avenue
(west of Alameda De Las Pulgas)
Ralston Avenue
(east of Alameda De Las Pulgas)
Ralston Avenue
(west of El Camino Real)
Cipriani Boulevard
(north of Ralston Avenue)
Alameda De Las Pulgas
(north of Ralston Avenue)
Alameda De Las Pulgas
(south of Ralston Avenue)
El Camino Real
(north of Ralston Avenue)
El Cami no Rea 1
(south of Ralston Avenue)
Belmont Canyon Road-central
(north of Ralston Avenue)
Christian Drive
(north of Ralston Avenue)
San Juan Boulevard
(just west of Cipriani Blvd.)
Route 92 Freeway
(west of Ralston Avenue)
Route 92 Freeway
(east of Ralston Avenue)
+ 6%
+ 3%
+ 3%
+ 5%
+ 2%
+ 2%
+ 8%
+ 2%
+ 2%
+<.5%
+<.5%
+ 30%
+ 60%
+ 51%
+ 2%
+ 1%
Increase In Existing PM
Peak Hour Traffic Due to
Planning Area Buildout
(vehicles per hour)
(from 2655 to 2810 vph)
(from 2615 to 2705 vph)
(from 2680 to 2765 vph)
(from 2500 to 2625 vph)
(from 2260 to 2315 vph)
(from 1620 to 1660 vph)
(from 970 to 1050 vph)
(from 1005 to 1030 vph)
(from 1695 to 1730 vph)
(from 3410 to 3425 vph)
(from 2840 to 2850 vph)
(from 235 to 305 vph)
(from 175 to 280 vph)
(from 205 to 310 vph)
(from 6400 to 6510 vph)
(from 5600 to 5645 vph)
Source: Goodrich Traffic Group
lsa
902
91 - lsa
Existing traffic safety concerns in the San Juan Hills planning area would be increased due to buildout traffic at the following locations:
o Along major roadways including Belmont Canyon Road and San Juan Boulevard and along internal roadways including Marsten Avenue, Upper Lock Avenue, Hi 11 crest Ori ve and Monte Cresta Ori ve. These streets cannot accommodate two-way traffic flow where vehicles are parked on both sides of the street. Driving patterns along these streets al so increase traffic safety concerns for pedestrians and bicyclists.
o At many internal intersections that have restricted sight distances and/or that lack stop signs.
o At the 1 eft-turn 1 ane on the Ralston Avenue eastbound approach to Cipriani Boulevard where buildout traffic would marginally increase the frequency of left-turning vehicles backing up and blocking through traffic during peak traffic conditions.
o At the Cipriani Baul evard intersection with San Juan Boulevard, where the increased number of vehicles turning 1 eft to San Juan Baul evard could increase the frequency of vehicle backups to and through the Ralston Avenue intersection.
o At the Green Court intersection with Christian Drive where the close proximity of the Green Court intersection to the Ralston Avenue intersection could increase potential conflicts between turning vehicles.
o On the Ralston Avenue westbound approaches to Christi an Ori ve and Belmont Canyon Road where increased volumes of right-turn vehicles would increase the chances for rear end ace i dents due to lack of right-turn deceleration lanes for turning vehicles.
o On the Ralston Avenue eastbound approach to Christi an Ori ve where the existing left-turn lane will probably not be long enough to accommodate existing and buildout traffic.
Cumulative Traffic Impacts. Traffic impacts of all proposed, approved, and under-construction developments in Belmont near the planning area were evaluated as part of this study. A list of projects considered, along with their respective development sizes, is shown in Table 6. 903
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TABLE 6
CUMULATIVE PROJECT TRIP GENERATION
PM Peak
Hour
Two-Way
Name Size Location Trigs
A. Davis Drive offices 84,000 SF Davis Drive 150
B. 1050 El Camino Real 8,136 SF 1050 El Camino 18
C. Safety Expansion Retail 8,453 SF El Camino at Emmett 75 D. Creekside Offices 41,100 SF 1070 Sixth 104
E. Creekside Condominiums 18 DU O'Neill and Sunnyslope 9 F. Island Park Mixed Uses Marine World Parkway 2,810
G. Belmont Hil 1 s Hospital Alternative Ralston, east of Chula 77 Expansion 2, 3, or 4 Vista Drive
3,243
Source: City of Belmont, Final EIR for the Proposed Belmont Hills Hospital Expansion by Earthmetri cs, June 1986; Addendum to the Fina 1 EI R for the Proposed Belmont Hills Hospital Expansion by Earthmetrics, October 1986. 904
93 lsa
Cumulative projects would generate a total of approximately 3,245 two-way p.m. peak hour trips. Evening peak hour cumulative volumes are shown on Figure 20. Cumulative volumes would produce significantly greater impacts on roadways and intersections near the San Juan Hills planning area than would traffic from buil dout of the planning area under the proposed Area Pl an.
However, there should be no increase in traffic or impacts on the roadways internal to the San Juan Hills planning area due to the cumulative projects.
With cumulative traffic, volumes on Ralston Avenue adjacent to the site would increase by up to 275 p.m. peak vph, while volumes on Cipriani Boulevard would increase by about 15 vph. Both roadways have available capacity to accommodate this increase in the planning area vicinity. Cumulative traffic would produce significant p.m. peak hour impacts at the Ralston Avenue intersections with the central access Belmont Canyon Road, Cipriani Boulevard, and El Camino Real, respectively using eight, five and eleven percent of total intersection capacity. Impacts would not be significant at Christian Drive or Alameda De Las Pulgas, where two and three percent of total intersection capacity would be used. Resultant p.m. peak hour operation with cumulative traffic added to existing and planning area buildout volumes would continue to be LOS A at Christian Ori ve and Belmont Canyon Road, and decrease to LOS C operation at Cipriani Boulevard, LOS E operation at Alameda De Las Pulgas, and LOS F operation at El Camino Real (see Table 4).
Traffic Impact on Residential Environment. Goodrich Traffic Group has developed an analysis methodology called Traffic Impact on Residential Environment or TIRE, to measure the impact of traffic on residents of residential or collector streets. TIRE is a numerical representation of a resident's perception of the affect of street traffic on activities such as walking, cycling and playing, and on daily tasks such as maneuvering an auto out of a residential driveway. Logarithmic index values ranging from zero, which represents the 1 east effect of t ra ffi c, to five, which represents the most severe traffic affect, express the level of perception to traffic volumes in one's 1 i vi ng environment. A change of O. I or more in index va 1 ues indicates that residents will perceive an impact on their living environment due to increased traffic volumes. Streets with TIRE levels above the midrange index of three, which corresponds to a volume of 300 vph, are trafficdominated, while lesser indices indicate streets with more residential activity.
Table 7 shows TIRE index values for road locations with the maximum accumulation of potential traffic due to buildout of the planning area. As shown, project area buildout traffic would produce a measurable impact on the environment of those residents living along Christian Drive and Marsten Avenue; and possibly, to residents living along Bishop Road, Skymont Drive, Belmont Canyon Road, Hillcrest Drive 1 Lower Lock Avenue, San Juan Boulevard, Alhambra Drive, Monte Cresta Drive, Sequoia Way, and Buena Vista Avenue. 905
94 TABLE 7
TRAFFIC IMPACT ON RESIDENTIAL ENVIRONMENT (TIRE)
Locations
Christian Drive
just north of Ralston
Belmont Canyon Road - central
access just north of Ralston
San Juan Boulevard
just west of Cipriani Boulevard
* Index Values
Existing
Volumes
3.2 3.4
3.3 Existing+
Planning Area
Buildout Volumes
3.4 3.5
3.5 lsa
*A change of .1 or more indicates that residents will perceive an impact on their living environment due to increased traffic volumes.
Source: Goodrich Traffic Group
906
95 lsa
Mitigation Measures
In addition to adoption of the mitigating policies of the Area Plan discussed above, the following measures are recommended to offset potential adverse traffic impacts of planning development:
I. New roadways through the San Juan Hills planning area are recommended to be built to the following minimum standards:
Width
20 ft
28 ft
36 ft
On-Street Parking Allowed
No
One side only
Both sides
2. Brush and landscaping within roadway rights-of-way should be trimmed back on intersection approaches where sight distances are limited.
3. A priority list should be developed to provide stop signs on lower volume approaches to internal intersections. Signs should be installed first at high accident locations, and as funds permit, at all other locations.
4. Right-turn deceleration lanes should be provided on the Ralston Avenue westbound approaches to Christian Drive and the central access Belmont Canyon Road.
5. A short, left-turn, storage lane should be provided on the northbound Cipriani Boulevard approach to San Juan Boulevard.
6. The 1 eft-turn 1 ane on the eastbound Ra 1 ston Avenue approach to Cipriani Boulevard should be 1 engthened by about 100 feet, or the maximum length possible without moving the existing street light in the median.
7. The 1 eft-turn 1 ane on the eastbound Ra 1 ston Avenue approach to Christi an Drive should be 1 engthened by about 100 feet prior to buildout of the Skymont area.
8. On-street parking prohibitions along one side of the street are recommended for San Juan Boulevard from Monte Cresta Drive to Cipriani_ Boulevard and for the central access Belmont Canyon road from Ralston to Hillcrest, if a majority of adjacent residents agree to the proposal. This would allow less congested traffic flow 907
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through the two highest volume locations on the San Juan Hills planning area roadways that are not wide enough to accommodate twoway traffic flow as well as on-street parking. It would also reduce the frequency of minor accidents between through traffic and vehicles parked on-street.
9. All new cul -de-sacs should have turnaround areas large enough to accommodate fire and emergency vehicles.
10. Pathways or sidewalks should be constructed on at least one side of a 11 new streets.
11. Green Court traffic should be rerouted to access Christian Drive via Marsten Avenue. A new access directly to Ralston Avenue to serve the Green Court area is not recommended due to its impact on Ralston Avenue traffic flow.
12. Additional through and/or turn lanes would be needed at the Ralston Avenue/El Camino Real and Ralston Avenue/Alameda De Las Pulgas intersections to provide acceptable peak hour operation under existing, planning area buildout, and cumulative volumes.
13. Separate signal phasing should be provided for the left-turn movements from Alameda De Las Pulgas to Ralston Avenue. 908
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CLIMATE AND AIR QUALITY
Setting
Climate. The Bay Area's climate, as with all of California coastal environs, is dominated by the strength and position of the semi-permanent high pressure center over the Pacific Ocean near Hawaii. This pressure center creates cool summers and mild winters with infrequent rainfall. A persistent cool daytime sea breeze maintains comfortable humidity levels. Unfortunately, the same atmospheric processes that create the desirable living climate also restrict the ability of the atmosphere to disperse air pollution. Portions of the Bay Area, particularly highly urbanized and poorly ventilated portions of the Santa Clara Valley, experience air pollution levels well in excess of established clean air standards.
Temperatures in Belmont, as determined from long-term climatic records in nearby Redwood City, average S9°F annually. The warmest afternoons in summer average in the low-SO's while winter mornings drop to around 40°F. Daily and season a 1 osc il 1 at ions of temperatures are sma 11 because of the moderating effects of the nearby oceanic heat reservoir. Temperatures in excess of I00°F or below 30° F are rare and in many years do not occur at all. In contrast to the steady temperature regime, rainfall is highly variable, and confined almost exclusively to the "rainy" period from early November to mid-April.
Belmont averages 19 inches of precipitation annually, but because much of the area's rainfall derives from the fringes of mid-latitude storms whose track is often erratic, and because the Peninsula topography causes substantial variations in rainfall intensity, there is considerable geographical and temporal variation in rainfall amounts.
Meteorology. Winds near the San Juan Hills area display several characteristic regimes. During the day, especially in summer, winds are from the west and northwest at 10-14 miles per hour as air is funneled through the Golden Gate and then diverges across the entire Bay Area. At night, especially in winter, the land becomes cooler than the water and a downslope flow off the Peninsula hills and a regional outflow toward the Golden Gate may develop. One other important wind regime occurs when a high pressure center forms over the western United States interior and brings hot air out of the Central Va 11 ey into the Bay Area. Winds from the southeast under these conditions create brief hot spells in late summer and early fall that generally yield the highest temperatures observed annually in the Bay Area.
Adequate daytime ventilation prevents any significant daytime stagnation of air pollutants in the Belmont area. Daytime airflow across the San Juan Hills planning area normally spends only a limited time over populated areas 909
98 lsa
resulting in baseline air pollution levels that are quite low. The moderate onshore breeze carries any l oca 11 y generated emissions southeastward into Santa Clara County. Daytime air quality problems occur mainly when the Pacific High pressure ridge sets up too close to shore and weak winds fail to adequately flush the Bay Area. The area of poorest ventilation tends to be more toward San Jose, but Belmont may experience slightly unhealthful levels of photochemical smog as well. Air quality concerns near the planning area, particularly in winter when the drainage fl ow is strongest, center on the localized accumulation of primarily automotive exhaust pollutants instead of the photochemically reacted species that are most prevalent on summer afternoons. Air fl ow from 1 i ght 1 y populated higher terrain areas west of Belmont is unpolluted when it arrives in Belmont. But slow wind speed and lack of turbulent mixing can lead to substantial ambient concentrations near major emissions sources.
In addition to winds that govern the horizontal rate and trajectory of air pollutants, the Bay Area experiences two characteristic temperature inversions that control the vertical depth in which pollutants are mixed. The daytime onshore flow of marine air is capped by a massive dome of warm air that acts like a giant lid over the regional airshed. As the clean ocean air moves inland, pollutants are continually added from below without any dilution from above. As this layer slows down in inland valleys of the basin and undergoes photochemical transformations under abundant sunlight, it creates unhealthful levels of smog (mainly ozone}. A second inversion forms at night as cool air pools in low elevations while the air aloft remains warm. These type of inversions trap po 11 utants near intensive traffic sources such as freeways and shopping centers forming localized violations of clean air standards called "hot spots".
Air Quality Standards. In order to assess the air quality impact of any proposed development, that impact, together with baseline air quality levels, must be compared to the applicable ambient air quality standards. These standards are the 1 eve 1 s of air qua 1 i ty considered safe, with an adequate margin of safety, to protect the public health and welfare. They are designed to protect people most susceptible to respiratory distress or infection including asthmatics, the very young, the elderly, people weak from other illness or disease, or persons in heavy work or exercise. These people are called sensitive receptors. Healthy adults can tolerate periodic exposure to air pollution levels well above these standards before adverse health effects are oberved.
The Clean Air Act Amendments of 1970 es tab 1 i shed nat i ona 1 Ambient Air Quality Standards (AAQS} with States retaining the option to adopt more stringent standards or to include other pollution species. Because California 910
99 lsa
already has standards in existence before Federal AAQS were established, and because of unique meteorological problems in the State, there is considerable diversity between State and Federal standards currently in effect in California, as shown in Table 8.
Baseline Air Quality. Existing and probable future levels of air quality near the San Juan Hills area can be inferred from ambient air quality measurements conducted by the Bay Area Air Quality Management District (BAAQMD) in Redwood City. This station is the only monitoring site in San Mateo County, and measures both regional pollution levels such as dust and, smog, as well as primary vehicular pollution·levels near busy roadways such as carbon monoxide (CO) and nitrogen oxides (NO�
). Table 9 summarizes the last
five years of published data from this monitoring station. As shown, air pollution levels are extremely low, attesting to the excellent ambient air quality found in the Belmont area.
Photochemical smog or ozone levels continue to exceed standards by a very small margin. The frequency of violations of the Federal standard for ozone has ranged from zero to two violations per year. Federal guidelines allow for one violation per year averaged over three years. Redwood City, and by inference Belmont, has met a one annual violation average limit for the first half of this decade and is therefore an attainment subarea within the larger Bay Area Basin ozone non-attainment area. Annual maximum ozone levels have varied considerably within a wide range. Although higher levels in the range are considered unhealthful for the most sensitive individuals, they are well below the first stage ozone alert levels of 0.20 parts per million (ppm) which is considered unhealthful for all receptor populations.
Measurements of carbon monoxide (CO) showed very low baseline levels with only one violation of the eight-hour CO standard recorded in five years.
Similarly, nitrogen dioxide {N02J levels, another indicator of the automotive exhaust pollution in the air around Belmont, have been very low with maximum annual N02 levels at 50 percent of the allowable maximum level.
Airborne dust levels rarely exceed the State standard, and no measurement in excess of the Federal particulate standard has been recorded in the past five years. An inhalable dust standard for particles of IO-micron diameter or less {PM-10) shows that isolated violations of the stringent California PM-10 standard may occur in Belmont, but levels are expected to be much lower than those found in other urbanized metropolitan areas of the country.
Air Quality Plans. The continued violation of the Federal ozone and CO standards in the Bay Area Air Basin requires that regional planning and air pollution control agencies prepare a regional Air Quality Plan {AQP). The AQP 911
100
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TABLE 8
AMBIENT AIR QUALITY STANDARDS
Pollutant Averaging Tim• California Standard• National Standard.-· Concentration Method Primary Secondary· Method
Oxidant 1 hour 0.10 ppm Ultraviolet - - -
(200 ug/ml
) Photometry
Ozone 1 hour - - 0.12 ppm Same as Primary Ethylene
(235 ug/ml) Standard Chemiluminescence
Carbon Monoxide 9.0 ppm Non-Dispersive Same as Non-0 ispersive 8 hour 10 mglm" (10 mg/ml ) Infrared (9 ppm) Primary Infrared
Spectroscopy Standards Spectroscopy
1 hour 20 ppm (NOIRJ 40 mg/ml (NDIR)
(23 mg/ml
) (35 ppm)
Nitrogen Dioxide Annual Average - 100 ug/ml Gas Phase Gas Phase {0.05 ppm) Chemilumi- Same as Primary Chemiluminescence
1 hour 0.25 ppm nescence - Standard
(470 ug/ml)
Sulfur Dioxide Annual Average - 80 ug/ml -
(0.03 ppm)
24 hour 0.05 ppm 365 ug/ml -
(131 ug/ml
) Ultraviolet (0.14 ppm) Pararosaniline Fluorescence
3 hour - - 1300 uglm"
(0.5 ppm)
1 hour 0.5 ppm - -
(1310 ug/ml
)
Annual Geometric 30ug/m3 - -
Suspended Mean
Porticulote PM10 - �oller
(PM10) 24 hour 50 ug/m3 - -
Suspended Annual Geometric - 75 ug/ml 60 ug/mJ
Paniculate Mean
Matter - High Volume
24 hour - 260 ug/m" 150 ug/m3 Sampling
Sulfates 24 hour 25 ug/m3 Turbidimetric - - -
Barium
Sulfate
Lead 30 day 1.5 ug/ml Atomic - - -
Average Absorption
Calenda:- - - 1.5 uglm" Same as Pri- Atomic
Quaner mary Standard Absorption
Hydrogen 1 hour 0:03 ppm Cadmium Hydro•• - - -
Sulfiae (42 ug/m3
) ide STRactan
Vinyl Chloride 24 hour 0.010 ppm Tedlar Bag
(C hloroethene) (26 ug/mJ
) Collection, Gas - - -
Chromatography
Visibility 1 observation In sufficient amount to
Reducing reduce the prevailing visibility
Particles to less than 10 miles when the
relative humidity is less than 70% - - -
Source: California Air Resources Board
912
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TABLE 9
BELMONT AMBIENT AIR QUALITY MONITORING SUMMARY
(Days standards were exceeded, and maxima
Pollutant/Standard 1981 1982
Ozone:
1-HR > 0.10 ppm 2 1
1-HR > 0.12 ppm 1 0
1-HR > 0.20 ppm 0 0
Max. 1-HR (ppm) 0.13 0.10
Carbon Monoxide:
1-HR > 20 ppm 0 0
8-HR > 9 ppm 0 0
Max. 1-HR (ppm) 12. 14.
Max. 8-HR (ppm) 6.7 6.0
Nitrogen Dioxide:
1-HR > 0.25 ppm 0 0
Max. 1-HR ( ppm) 0.09 0.08
Total Suspended Particulates:
24-HR > 100 ug/m 0/61 0/61
24-HR > 260 ug/m 0/61 0/61
Max. 24-HR (ug/m) 73. 88.
Lead Particulates:
1-MO > 1.5 ug/m 0/12 0/12
Max. 1-MO (ug/m) 0.31 0.47
Sulfate Particulates:
24-HR > 25 ug/m 0/61 0/61
Max. 24-HR (ug/m ) 6.5 7.2
Source: California Air Resources Board
Summary of Air Quality Data, 1981-1985
BAAQMD Redwood City Monitoring Station.
for periods indicated).
YEAR
1983 1984 1985
8 9 5
2 0 1
0 0
0.17 0.11 0.13
0 0 0
1 0 0
15. 13. 14.
9.6 5.6 6.4
C) 0
O. lu 0.09 0.13
0/60 0/61 2/61
0/60 0/61 0/61
93. 92. 113.
0/12 0/12 0/12
0.38 0.34 0.22
0/60 0/61 0/61
9.0 9.4 10.8
lsa
913
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Quality Plan (AQP). The AQP must outline the measures by which both stationary and mobile sources will be controlled in order to achieve all standards by the Clean Air Act deadlines. For the Bay Area Air Basin, which includes portions of a nine county area, a Bay Area Air Quality Plan was jointly prepared by the Association of Bay Area Governments (ABAG), the Metro po 1 i tan Transportation Cammi ss ion and the BAAQMD. The current AQP was prepared in 1982, and predicts attainment of all national clean air standards within the basin by 1987. Current ozone trends in the basin do not support the prediction, but the BAAQMD continues to maintain that attainment of the ozone standard is imminent. Bay Area air qu�lity has improved within the last 10 to 15 years in response to aggressive pollution control programs, and is certainly far better than in Southern California, however nominal violations of the ozone standard will most likely continue beyond 1987.
Potential Impacts
Potential development under the proposed Area Plan would be approximately 26 percent less than the permitted by the existing General Plan. Traffic generated by new development in the planning area would be less under the Area Plan and consequently, air quality impacts would also be less. Future development in the San Juan Hills planning area would impact air quality primarily through transportation-related vehicular exhaust emission. The proposed San Juan Hil 1 s Area Pl an rel ates to the AQP through the growth assumptions made by ABAG for the region. ABAG uses the genera 1 p 1 ans from cities (including the Belmont General Plan) to predict transportation-related air pollution sources based on future patterns of population, housing, employment and 1 and use. To the extent that the proposed project has been anticipated in the ABAG growth assumptions, and depending on the implementation of available transportation control measures, the regional emissions from development under the Area Plan will not have a significant air quality impact.
Vehicular Emissions Impacts. Potent i a 1 resident i a 1 deve 1 opment in the planning area can impact air quality through traffic and associated mobile source emissions. Any single project, particularly low density residential development such as permitted by the proposed San Juan Hills Area Plan, does not create emissions in sufficient quantity to threaten air quality standards.
Rather, the emissions from any one residential project would mix with those of similar projects throughout the Bay Area and the cumulative impact would ultimately contribute to the air basin's inability to meet clean air standards.
Locally, planning area buildout traffic would be added to surrounding roadways (primarily on Ralston Avenue) and create microscale impacts at 914
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receptors located adjacent to traveled roadways. Planning area buildout traffic would contribute vehicular emissions and would reduce vehicular speeds resulting in additional pollutant generation. On a regional scale under buildout, the additional trip generation spread over space and time, would have a negligible local impact when compared to the existing levels of traffic on the Belmont area roadway system.
Based on a trip generation rate of 10.0 daily trips per dwelling unit and an average residential trip length of around 6.2 miles per trip, buildout of the San Juan Hills planning area under the Area Pl an would generate 3, 720 daily trips and add 23,060 vehicle miles traveled {VMT) to the regional VMT burden. Compared to projections of around 100,000,000 daily VMT expected to be driven within the air basin during the next decade, development of the San Juan Hills would add only a small fraction to the overall burden. The primary air quality impact of such growth would therefore tend to be more localized.
Development-related air pollution emissions generation were estimated by combining information on trip and VMT generation with vehicular emissions characteristics. The BAAQMO's guidelines for assessing project and plan air quality impacts provides generalized emissions factors and cold-start corrections data as a function of land use. These values were applied to the San Juan Hills Area Plan buildout projection to generate an emissions burden as shown in Table 10. These data show development-related emissions comparisons for future years as if the remaining uni ts were a 1 ready bu i 1 t.
Emission 1 eve 1 s range from a few pounds per day of particulates and sulfur dioxides, tens of pounds of nitrogen oxides {NO ) and total hydrocarbons {THC), and hundreds of pounds of carbon monoxide (�O). For all species with significant emission rates, future emissions would be substantially lower than what they would be for a comparable existing residential development.
A measure of the significance of the mobile source emissions burden can be gained by comparing planning area buildout emissions to regional totals as shown in Table 11. As shown, the planning area buildout's share of basin and county-wide emissions would be ins i gni fi cant. The BAAQMD has established several general tests for potential regional significance as a guide for placing the regional vehicular emissions burden into proper perspective. If the proposed development creates less than 150 pounds of exhaust pollutants for all species except CO, and if the development represents less than a one percent increase in County-wide transportation-related emissions, then the regional impact of the development's mobile source emissions may be considered insignificant. Potential buildout of the San Juan Hills planning area under the proposed Area Plan meets these insignificance guidelines. 915
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TABLE 10
VEHICULAR SOURCE AIR EMISSIONS DUE TO
SAN JUAN HILLS PLANNING AREA BUILDOUT
Emissions (tons/day)
Pollutant Species: 1985 1990
Carbon Monoxide 0.43 0.32
Total Organic Gases 0.05 0.03
Nitrogen Oxides 0.04 0.03
Sulfur Dioxide 0.01 0.01
Suspended Particulates 0.01 0.01
Source: BAAQMD Air Quality and Urban Development Guidelines 1995
0.28 0.03
0.03 0.01
0.01 lsa
2000
0.28 0.03
0.03 0.01
0.01 916
105
TABLE 11
MOBILE SOURCE EMISSIONS COMPARISONS
San Juan Hills Area Plan
Development Share of:
Bay Area Air Basin - Total
Air Basin - Transportation Only
San Mateo County - Total
County - Transportation Only
Carbon
Monoxide
0.01%
0.02%
0.10%
0.11%
Total
Organics
0.01%
0.02%
0.05%
0.08%
Source: BAAQMD Air Quality and Urban Development Guidelines lsa
Nitrogen
Oxides
0.02%
0.07%
0.08%
917
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While regional impacts would be minimal, additional traffic on local roadways may contribute to small pollution increases, generally CO, adjacent to San Juan Hills access roadways. As indicated in the Traffic and Circulation section of this EIR, the bulk of external traffic from the San Juan Hills area would use Ralston Avenue. It is estimated that development of the projected 372 units may add about 150 vehicles per hour to a projected future rush hour non-project load of slightly under 3,000 vehicles per hour along Ralston Avenue between Christian Drive to the west and Cipriani Boulevard to the east. Based on the worst-case assumption that rush hour would coincide with a wind stagnation period with winds parallel to Ralston and a very stable low-level temperature inversion, microscale_ carbon monoxide impacts (i.e. potential "hot spots") have been estimated using the BAAQMD's CALINE3 model. The model results are summarized in Table 12.
As shown in Table 12, existing CO levels within immediate proximity to the roadway may be very close to the hourly standard of 20 ppm, and probably exceed the allowable eight-hour limit when background CO levels are taken into account. Future CO levels would be lower than at present even with increased traffic on Ralston Avenue from both San Juan Hills planning area buildout and other cumulative growth because continued pollution improvements in the overall vehicle fleet would more than off-set the traffic increase. Planning area buildout would create a slight CO increase, but the incremental impact would be much less than one ppm. These calculations suggest that the microscale impact of buildout in the San Juan Hills planning area, as with the regional scale, would not be significant.
Construction Activity Impacts. During consruction activities for planning area development, clearing, grading, utility excavation and vehicle movement on unpaved surfaces would generate large volumes of dust that prevailing daytime onshore winds would blow southeastward. The Environmental Protection Agency (EPA) and BAAQMD estimate that each acre of soil disturbed during temporary residential construction can add about seven tons of dust to the air unless vigorous dust control measures are employed. For single family residences, the disturbance area during construction typically amounts to about one-quarter acre per unit.
The ultimate development of 372 units in the San Juan Hills planning area would involve disturbance of approximately 93 acres for homesites plus additional grading for roadways and would result in potential fugitive dust nuisance sources. Without imp 1 ement i ng any fugitive dust cont ro 1 measures, planning area buildout would cause about 670 tons to be added to the local airshed during the construction of these units. However, the BAAQMD requires employment of dust control measures that prevent the formation of a visible dust cloud, or the creation of a dust settling nuisance beyond the project 918
107
TABLE 12
VEHICULAR EMISSIONS - MICROSCALE IMPACT ASSESSMENT
(Carbon Monoxide Exposure at Roadway Edge - ppm)
Scenario/Exposure Period
Existing Traffic:
One Hour -
Eight Hour -
Future (1995) - No Growth
One Hour -
Eight Hour -
Future (1995) With Project
One Hour -
Eight Hour -
Ralston/
Cipriani
18.4 12.0*
15.6 10.0*
15.7 10.1*
Future (1995) Project+ Cumulative Growth
One Hour -
Eight Hour -
16.0 10.3*
Intersections:
Ralston/
Belmont Cyn.
17.9 11.6*
15.3 9.8*
15.4 9.9*
15.7 10.1*
*=possible violation of 8-hour state and federal CO standards Source: BAAQMD Air Quality and Urban Development Guidelines Ralston/
Christian
17.8 11.5*
15.2 9.7*
15.5 9. 9�t
15.7 10.1*
lsa
919
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property line. Measures, including regular watering, early paving and prevention of soil spillage on traveled roadways, would reduce dust generation by 50 to 75 percent. Total dust generation during buildout with implementation of dust contra l measures would range from 170 to 340 tons.
Although this amount of dust generation is substantial, it would be spread out over a large area and over many years of individual parcel construction, and would not create perceptible particulate impacts much beyond any single construction site. Construction-generated dust is usually chemically inert and small enough to be filtered by human breathing passages. Construction dust would not represent a significant heal th concern. It may, however, create a soiling nuisance as these relatively large dust particles settle out on nearby parked cars, outdoor furniture, foliage and other horizontal surfaces.
Construction activities al so generate considerable combustion emissions from on-site heavy equipment and off-site trucks hauling dirt, concrete, wood, and other building materials. The California Air Resources Board estimates that each acre of residential construction requires about 300,000 Brake Horsepower Hours to build out one acre of residential land use. Assuming that future development in the San Juan Hills would involve approximately 93 acres of construction areas as noted above, and assuming that heavy equipment is primarily diesel-powered, the following emissions would result during the buildout period of the planning area:
Reactive Organic Gases
Carbon Monoxide
Nitrogen Oxides
Suspended Particulates
Sulfur Dioxide
45.5 tons
93.4 tons
319.5 tons
19.3 tons
36.4 tons
These emission l eve 1 s would be substantial , but would be spread over a wide area and occur over a number of years of activity. No single receptor would be exposed to any significant portion of these emissions. Any perceptible impacts would be confined to an occasional odor of diesel exhaust near the equipment itself. As with the fugitive particulates, construction equipment impacts would constitute a minor potential nuisance rather than any adverse health impact.
Miscellaneous Air Quality Impacts. Residential development introduces a number of small additional sources of air emissions that are insignificant on an individual basis, but which become significant when considered cumulatively. Many of these sources are so small as to not be attributable to any single development, but nevertheless represent a non-negligible portion of the air basin pollution inventory. Such sources have been aggregated by the BAAQMD into a total burden factor per dwelling unit. That factor was applied 920
109
TABLE 13
DEVELOPMENT RELATED TOTAL EMISSIONS (tons/year)
Pollution Species: Mobile
Carbon Monoxide 102.2
Total Organics 11.0
Nitrogen Oxides 11.0
Sulfur Dioxide 3.6
Suspended Particulates 3.6
Source Contribution
Stationary
4.5 8.5
1.5 0.1
0.5 Source: BAAQMD Air Quality and Urban Development Guidelines lsa
Total
106.7
19.5 12.5
3.7 4.1
921
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to the potential buildout of 372 dwelling units in the planning area and is summarized in Table 13. The mobile source contribution is seen to dominate most pollution categories, but reactive organic gases from paints, lawnmowers, gas stations, and cleaning products associated with individual residential units can create a substantial annual emissions burden.
Mitigation Measures
Since most development-related air quality impact derives from automotive sources which are beyond the control of project sponsors or local regulatory agencies, effective mitigation is difficult. Given the fact that both regional and local impacts are well within the basin airshed's capacity, there is little need to develop stringent air quality mitigation measures for the San Juan Hills planning area.
Although there are no unacceptable air quality impacts from the Area Plan or buildout of the planning area, there are a number of standard mitigation measures that should be considered in development planning to further minimize any potential for unacceptable air quality impacts. These are as follows:
1. Implement aggressive dust control measures as required by local ordinance and BAAQMD Rules and Regulations.
2. Perform major grading in spring when soil moisture is high to minimize fugitive dust generation.
3. Carry out major soil disturbance between 8 a.m. to 4 p.m. when winds are strongest to reduce the amount of dust settling out on nearby receptors and to obtain better areawide dispersion of any fugitive dust.
4. Encourage a 1 tern ate modes of transportation through provision of sidewalks, bike paths and a covered transit stop along Ralston Avenue to reduce dependence on cars as the sole means of transportation.
922
NOISE
Setting
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Sound is mechanical energy transmitted by pressure waves in a compressible medium such as air. The decibel (dB} scale is a way of measuring sound levels. Sound level intensities are extremely variable and can change over one mi 11 ion ti mes within the range of human hearing. To expres-s this variability, a logarithmic scale called the decibel (dB) scale is used to keep sound intensity numbers at a manageable level. Since the human ear is not equally sensitive to all sound frequencies within the spectrum, human response is factored into sound descriptions in a process called "A-weighting", written as dB(A).
Noise exposure is typically expressed as a statistical description of a given sound level that is exceeded during a portion of an observation period.
Lio, Lso and Lgo are expressions indicating the relative amount of time that noise levels are exceeded, with the number (i.e., 10, 50, 90} indicating the percent of time a given noise level is exceeded during the observation period.
Because community receptors are more sensitive to unwanted noise intrusion during the evening and at night, State law requires that for planning purposes, an artificial dB increment be added to noise levels in a 2f -hour
noise descriptor called ·the Community Noise Equivalent Level (CNEL). An interior CNEL of 45 dB(A} is mandated for multiple-family dwellings, and is considered a desirable noise exposure for single-family dwelling units as well. Typical noise attenuation within residential structures with closed windows is about 20 dB, and therefore 65 dB CNEL is a typical exterior noise exposure design standard for new residential dwellings in California.
The Noise Element of the City of Belmont General Plan specifies a maximum desirable exterior noise exposure of 65 dB(A} for residential and other noise sensitive uses, and an exterior 75 dB(A) level for less sensitive uses such as commercial and industrial developments. With the inclusion of adequate noise insulation, a 70 dB(A) level is considered conditionally acceptable for noise sensitive development such as residences, churches and schools. The outdoor lcNEL is a measure of the cumulative effect of individual noise events averaged over a 24-hour period and weighted by the time of occurrence. Noise levels measured between 10:00 pm and 7:00 am receive a 10 decibel (dB} penalty, and noise levels measured between 7:00 pm and 10:00 pm receive a 15 dB penalty. The penalties are added, because noises seem 1 ouder than they really are between these hours.
923
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environment under this exposure level will seem excessively noisy, but nevertheless marginally tolerable.
The Noise Element of the Belmont General Plan identifies major sources of noise in the community and presents goals and policies to minimize the adverse effects of noise. According to the General Plan, approximately 30 houses in the San Juan Hills planning area are presently exposed to Lio Noise Levels of 65 dBA or greater. Most of these houses are 1 ocated in the Cipriani area, about six are located in the Plateau area, and none are located in the Skymont area.
Existing noise levels within the San Juan Hills planning area originate mostly from vehicular noise from nearby arterial roadways and freeways.
Occasional noise intrusions from recreational off-road vehicles or from aircraft overflights may occur, but they contribute little to the background noise levels. To characterize current noise levels in and around the planning area, a brief on-site noise survey was conducted on November 10, 1986. Hourly noise levels adjacent to Ralston Avenue were monitored using standard CalTrans roadway noise monitoring protocols. In addition, a noise survey was conducted at several locations within the planning area itself. Monitoring was conducted using a B&K Model 2230 Sound Level Meter operating in the A-weighted Leq monitoring mode.
Noise levels within the San Juan Hills planning area on Belmont Canyon Road near Ra 1 ston Avenue were 55. I dB, and decreased to 43. 9 dB at the farthest point from Ralston Avenue. In the parking lot at Ralston Intermediate School 50 feet from the roadway divider, the hourly Leq reading was 64. 2 dB. The Ra 1 ston Avenue readings, in conjunction with concurrent traffic counts and speed checks, were used to calibrate the federal highway traffic noise prediction model {FHWA-RD-77-108, initialized with the latest California vehicle noise emissions data). The initial calibration run showed that the FHWA Model, which cannot fully account for the topographical screening created by complex topography of the planning area, slightly overpredicts observed noise levels along Ralston Avenue, and significantly overpredicts noise levels within the San Juan Hills planning area. To account for this deficiency, a correction factor determined during the model calibration exercise was app 1 i ed to the FHWA Model which was then used to calculate existing noise levels along Ralston Avenue and along several local area roadways.
Table 14 summarizes modeled estimates of existing noise exposure in the western Belmont area. As shown, the 65 Lio contour generally extends about 90 feet from the Ra 1 ston roadway centerline. In areas of lighter traffic a 1 ong Cipriani Boulevard, Hillcrest Boulevard and Christian Drive, the 65 dB Lio 924
113
TABLE 14
EXISTING NOISE CONTOURS ADJACENT TO RALSTON AVENUE
Location:
Ralston E of Cipriani
Ralston W of Cipriani
Ralston E of Christian
Ralston W of Christian
Cipriani N of Ralston
Hillcrest N of Ralston
Christian N of Ralston
LIO Level
at SO'
68.3 69.0
68.7 68.9
64.5 58.3
57.1 Distance to
65 dB LIO
81'
90'
87'
90'
<SO'
<SO'
<SO'
Distance to
60 dB LIO
175'
194'
187'
193'
98'
<SO'
<SO'
lsa
Distance to
55 dB LIO
377'
419'
404'
416'
212'
82'
67'
Note: Distances to 65, 60 and 55 LlO's north of Ralston are actually much less because calculations do not take into account terrain-induced "noise shadow" effects.
Source: FHWA Traffic Noise Prediction Model (FHWA-RD-77-108) 925
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contour is within 50 feet of the roadway centerline. The values for the 60 and 55 db Lio contours are generally not valid north of Ralston Avenue because sound is essentially a straight-1 ine transmission process and the downhill residences do not perceive Ralston Avenue traffic sources due to the sharp drop in terrain and any intervening structures. The formation of this "noise shadow" creates a rapid transition from an urbanized traffic noise environment along Ralston Avenue to a semi-rural quiet environment within the downhill residential community. The preservation of this low existing noise exposure is an important consideration in evaluating the proposed San Juan Hills Area Pl an.
Potential Impacts
Development under the proposed Area Plan would result in fewer units than buildout under the existing plan. Traffic volumes associated with Area Plan buildout would be correspondingly lower. Since ambient noise levels in the San Juan Hills planning area are primarily related to vehicular noise, future noise levels would be lower under the Area Plan than under the General Plan.
Two characteristic noise sources are typically identified with the type of residential development that could occur in the San Juan Hills planning area under the proposed Area Plan. Construction activities, especially heavy equipment, would create short-term noise increases in the planning area.
Vehicular traffic on streets in the planning area could also create a noise exposure which is higher than the noise levels currently experienced.
Construction Noise. Potential temporary construction noise impacts would vary considerably because the noise strength of construction equipment ranges widely with the type of equipment and activity level. Short-term construction noise impacts tend to occur in discrete phases including site clearing and earth-moving activities first, then foundation and roadway construction, and finally finish construction. The site clearing and earth-moving sources are the noisiest with equipment noise ranging from 73 to 95 dB{A) at 50 feet from the source. Point sources of noise emi ss i ans are atmospheri ca 11 y attenuated by a factor of 6 dB per doubling of distance. Based on a desirable interior noise exposure level of 45 dB, and assuming 20 dB noise reduction within residences with closed doors and windows, 65 dB represents a maximum desirable exterior noise exposure. The quieter construction noise sources would not be detectable by enclosed residences within about 200 feet from the source, while the loudest construction noise sources would require five distance doublings {to 1,600 feet from the source) to reduce the 95 dB{A) source strength to an acceptable 65 dB{A) exposure level.
926
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Construction noise sources do not strictly rel ate to a noise standard because they occur only during selected times and the source strength varies sharply with time. But potential construction noise levels do indicate the need to maintain a suitable distance buffer or erect a temporary noise barrier between the loudest noise sources and nearby occupied dwellings. The penalty associated with noise disturbance during quiet hours and the nuisance factor accompanying such disturbance usually leads to time limits on construction activities imposed as conditions on construction and use permits. The hours from 7 a.m. to 5 p.m. during weekdays are typically the allowed times for construction activities if there are occupied dwellings within a reasonable exposure zone surrounding the construction site. Materials handling and small stationary noise sources have lower initial noise levels, which makes their corresponding noise impact zones smaller during later phases of construction.
Because of 1 ow ambient noise 1 eve 1 s, however, and the fact that the canyon topography of the planning area creates echo effects that limit the normal sound wave dispersion process, the area is sensitive to unnatural noise intrusion and even the less noisy construction sources would pose a noticeable daytime noise nuisance.
Vehicular Noise. Long-term noise concerns from buildout of the planning area under the San Juan Hills Area Pl an center primarily on mobile source emissions on Ralston Avenue and on the primary access roadways from the planning area onto Ralston Avenue. These concerns were addressed using the FHWA Model in the same manner as the existing noise environment characterization. The mode 1 calculates the L
�q noise 1 eve 1 for a particular
reference set of input conditions, and then makes a series of adjustments for site-specific traffic volumes, distances, speeds; or noise barriers. Table 15 summarizes the Lio level at 50 feet from various roadway centerlines for existing traffic; for development of another 372 residential units within the San Juan Hills planning area, and for other cumulative area growth that would use the analyzed roadways.
A one dB increase in noise level is considered a perceptible increase under very quiet conditions while a two to three dB increase becomes noticeable when the sound is superimposed upon typical interior noise levels in a house. Any increase beyond five dB is immediately perceptible. Impacts associated with buildout under the Area Plan are less than one dB, except on lightly used Hillcrest Boulevard and Christian Drive where development would add 1.2 dB and 2.4 dB, respectively, to existing levels. These increased dB levels would be noticeable, but would be considered insignificant because they would remain below the 65 dB Lio level, which is considered marginally acceptable as mandated in the Noise Element of the Belmont General Plan. The anticipated buildout of San Juan Hills planning area would not create unacceptable noise exposure as specified in the Noise Element. Table 15 shows 927
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TABLE 15
PROJECTED NOISE CONTOURS ADJACENT TO RALSTON AVENUE
LIO Level of SO' from Roadway Centerline (feet):
Location: Existing Future w/PROJ Future CUM GROWTH
Ralston E of Cipriani 68.3 68.5 68.8
Ralston W of Cipriani 69.0 69.1 69.3
Ralston E of Christian 68.7 68.8 69.3
Ralston W of Christian 68.9 69.2 69.6
Cipriani N of Ralston 64.5 64.8 64.8
Hillcrest N of Ralston 58.3 59.5 59.5
Christian N of Ralston 57.1 59.5 59.5
Distance to 65 LIO Contour from Roadway Centerline (feet):
Existing Future W/PROJ Future CUM GROWTH
Ralston E of Cipriani 81' 84' (+3') 88' (+4')
Ralston W of Cipriani 90' 92' (+2') 96' (+4')
Ralston E of Christian 87' 88' (+1') · 95' (+7')
Ralston W of Christian 90' 93 (+3�) 99' (+6')
Cipriani N of Ralston <SO' <50' <SO'
Hillcrest N of Ralston <SO' <50' <50'
Christian N of Ralston <SO' <SO' <SO'
Distance to 60 LlO Contour from Roadway Centerline (feet):
Existing Future W/PROJ Future CUM GROWTH
Ralston E of Cipriani 175' 181' (+6') 190' (+9')
Ralston W of Cipriani 194' 197' (+3') 206' (+9')
Ralston E of Christian 187' 190' (+3') 204' (+14')
Ralston W of Christian 193' 201' (+8') 214' (+13')
Cipriani N of Ralston 98' 102' (+4') 103' (+l')
Hillcrest N of Ralston <SO' <SO' <SO'
Christian N of Ralston <50' <SO' <SO'
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that the expansion of the 65 dB Lio contour would be a maximum of three feet along Ralston Avenue due to increased planning area traffic, and would be a maximum of seven feet when other cumulative growth is included. This expansion, however, would be due to an increase in the Lio level of about 0.5 dB which is not a perceivable increase within the normal framework of existing background traffic noise along Ralston Avenue.
Without detailed site plans of potential buildout in the planning area, it is impossible to determine if the limited expansion of the 65 Lio contour would encompass any new noise sensitive receptor sites not already within the 65 dB Lio exposure zone. Ralston Intermediate School has more than adequate setback to be protected, but there may be an isolated dwelling unit fronting onto Ralston Avenue frontage that would fall within the 65 Lio contour.
However, given the small absolute increase in noise level, the vehicular noise associated with buildout in the San Juan Hills planning area is not expected to create significant noise intrusions either within the planning area or along its primary access roadways.
Mitigation Measures
Noise levels would increase nominally with buildout under the San Juan Hills Area Pl an and from other cumulative growth. In order to maintain the rura 1 -type noise environment current 1 y observed within the community, the following mitigation measures should be adopted:
1. Construction noise near noise-sensitive receptors should be limited to daytime hours between Monday and Friday, (i.e., from 7 a.m to 5 p.m.).
2. Any stationary on-site noise sources including, but not limited to, compressors, generators, or power saws should be equipped with hospital grade mufflers for engine driven sources, or should be surrounded by a temporary plywood enclosure as a noise baffle.
3. To reduce the small (0.5 to 1 dB) Lio increase from planning area buildout and other cumulative growth traffic, reduced vehicle speeds should be promoted; and noisy vehicles, including construction trucks, should use the least noise sensitive routes.
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PUBLIC SERVICES AND UTILITIES
Fire Protection
Setting. The South County Fire Department has two stations which provide service to the San Juan Hills planning area. Station #3 is located at the corner of Cipriani Boulevard and Ralston Avenue, and Station #2 is located at Ralston Avenue and Granada Street. Each station is staffed by a minimum of three people on duty 24 hours a day and has one fire engine. The South County Fire Department dispatches fire fighters, two fire engines and one ladder truck in response to structure and grass fires. Response time to locations within the p 1 ann i ng area is two to four minutes. The current Insurani e
Services Office ( ISO) rating for the San Juan Hil 1 s planning area is 3 .
Back-up fire protection services are available through the California Department of Forestry facilities located near Hillcrest Boulevard and Ralston Avenue, and through the City of San Mateo Fire Department located at De Anza Boulevard and Highway 92. The South County Fire Department also responds to emergency medical requests (Captain Doug Fry, South County Fi re Department, personal communication).
The 1985 Uniform Fire Code has been adopted by the City of Belmont with amendments to the Code. Amendments include standards for minimum width on private streets (28-foot wide streets with no parking and 32-foot wide streets with parking on one side). The Uniform Fire Code also requires any dwelling unit over 3,000 sq. ft. to have an indoor sprinkler system (Hank Schmidt, South County Fire Department, personal communication).
The Fire Department currently has difficulty responding to service calls near the bottom of Laurel Creek Canyon. For safety reasons, the fire engine trucks must be driven slowly going downhill. This safety requirement, coupled with the relatively long distance from Fire Stations #3 and #2 to homes in Laurel Creek Canyon, presents access di ffi cult i es for the Fi re Department (Hank Schmidt, South County Fire Department, personal communication).
Potential Impacts. Residential buildout under the proposed Area Plan would not result in a significant increase in requests for fire protection services. The proposed development standards promote housing along existing improved roads, and in cul-de-sacs. Other proposed development standards under the density transfer program would result in fewer, but more densely developed areas (i.e. the Horse Ranch and designated "receiver" sites near lThe ISO rating is an insurance classification ranging from 1 {best) to 10 (worst).
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Bishop Road). This pattern of development would lessen the access problems that the Fire Department presently encounters when responding to calls in Laurel Creek Canyon and lower San Juan Canyon. Increased residential development in Laurel Creek Canyon under the proposed Area Plan could exacerbate existing access problems associated with steep road gradients and long distances.
The proposed emergency access road between the Skymont neighborhood and San Juan Boulevard would improve fire protection services to Skymont and the designated receiver sites near Bishop Road. The clustered development pattern promote� by the Area Plan (as opposed to a scattered development pattern) would allow the Fire Department to more effectively respond to fire emergencies. Clustered deve 1 opment may a 1 so 1 es sen the frequency of fires spreading from residential areas to open space areas since fewer individual areas, and associated potential fire sources, would be developed.
The following measures are included in the Area Plan and would offset potential adverse effects:
o All development must comply with the 1985 Uniform Fire Code and the 1985 Building, Mechanical and Plumbing Codes and the City of Belmont's amendments.
o Any development or improvement to infrastructure associated with meeting fire flow requirements should be financed by the developer.
Mitigation Measures. In addition to the measures included in the Area Plan, the following measure is recommended by the Fire Department:
I. Residential development in the bottom of Laurel Creek Canyon, and other relatively inaccessible areas, should be encouraged to include indoor sprinkler systems and fire-retardant roofs.
Police Protection
Setting. The Belmont Police Department, located at 1215 Ralston Avenue, provides police protection services to the San Juan Hills planning area. The planning area is under the surveillance of Beat #2 which covers the area north of Ralston Avenue to East Laurel Creek Road, between Adelaide Way to the west and Notre Dame Avenue to the east (Captain Don Davis, Belmont Police Department, personal communication).
Emergency police service response time to the planning area is about one minute and non-emergency response time is from thr�e to five minutes. There 931
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is an indiscernible difference in response time between the three neighborhoods in the planning area. Calls for police protection services in the planning area are usually related to noise complaints, assaults, home burglaries, and traffic accidents (Lieutenant Joe Perucci, Belmont Police Department, personal communication}.
The Po 1 ice Department does not experience significant access prob 1 ems between project area neighborhoods except on Marburger Avenue during the winter months. Occasionally police vehicles get stuck in the mud while responding to calls. The westernmost entrance to Belmont Canyon Road currently serves as an adequate entry/exit point between the Skymont and Plateau neighborhoods. San Juan Boulevard and Monte Cresta provide adequate access routes to Laurel Creek Canyon and the Cipriani neighborhood, respectively (Captain Don Davis, Belmont Pol ice Department, personal communication}.
Potential Impacts. Under the proposed Area Plan, overall impacts on police protection services are expected to be insignificant. Since potential deve 1 opment under the Area Pl an would be similar to existing deve 1 opment, service requests are not expected to change substantially in character or frequency, and thus additional police protection services would probably not be required (Captain Don Davis, Belmont Pol ice Department, personal communication}.
Improving and maintaining Marburger Avenue would provide year-round through access between the Plateau and Cipriani neighborhoods, thereby supplementing existing entry/exit points on Ralston Avenue. The proposed emergency access road linking Skymont to the rest of the San Juan Area would likewise increase access and police protection capabilities.
Mitigation Measures. None would be necessary.
Road Development and Maintenance
Setting. There are three types of roadways present in the San Juan Hills Area: improved streets, unimproved streets and paper streets. The 1 ocat ion of these roadways and the areas that they provide access to are shown in Figure 4.
Most existing roadways in the San Juan Hills area are improved roads.
Some of these roadways are be 1 ow standard width and 1 ack on-street parking, curbs, gutters and sidewalks. The current City standard for road width is 30 feet of paving with a sidewalk on each side and a total right-of-way of 50 feet. A 28-foot width is the standard for private streets. For extensions of 932
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roads, the City a 11 ows new roads to match the width and characteristics of existing roads. Due to natural topography, many streets, especially those that provide access to East Laurel Creek and Lower San Juan Boulevard, have very steep gradients. There are unimproved dead ends on many streets in the San Juan Hills planning area with inadequate turn-around areas for emergency vehicles. The Skymont area has only one point of access from Ralston Avenue (Christian Drive} which could hinder emergency access.
There are four unimproved roads in the San Juan Hills planning area.
Residents regularly use two of these roads - Upper Lock Avenue and Marburger Avenue - to get from the Plateau neighborhood to San Juan Boulevard and intervening residences. The road surface on Upper Lock/Marburger Avenue is unpaved, uneven and has many ruts from drainage across and down the roadway.
These roads are often impassable to normal vehicles during the winter months.
In addition, Marburger Avenue crosses an area which is identified as a critical geologic hazard in the geologic study by William Cotton and Associates (see the Geology and Soils section of this EIR}.
Marsten Avenue and Green Court are the other two unimproved roads. They are similar in physical appearance to Marburger Avenue and Upper Lock Avenue, but because they traverse flatter slopes, they have 1 ess eros i ona 1 damage.
Marsten Avenue links the Skymont area to the Horse Ranch property; and Green Court is the access road to the Horse Ranch.
Paper streets are streets that were proposed for eventual development at the time of subdivision to provide landowners with through access. These streets include Bartlett Way, Naughton Avenue, Lower Lock Avenue, East Laurel Creek Road, Marsten Avenue, Alhambra Drive, Monte Cresta Drive, San Ardo Way and a frontage road on Ralston Avenue. Portions of these streets have not been developed, as identified in Figure 4. Portions of Bartlett Way, Naughton Avenue, and Lower Lock Avenue traverse areas with critical geologic hazards as identified in the geologic study by William Cotton and Associates.
In 1926-1927, when road dedication of the above paper streets occurred, the City accepted maintenance responsibilities for only three streets: Monte Cresta Drive, and Upper and Lower Lock Avenues. Although the City accepted dedication of portions of some streets which were located partially within City limits and partially in San Mateo County, the City did not accept maintenance responsibility of Marsten Avenue, Marburger Avenue and East Laurel Creek Road. Naughton Avenue and Green Court were outside of the City limits at the time and no dedication for these streets has occurred. Table 16 indicates the status of paper and unimproved streets in the planning area. 933
Dedication and
Maintenance
Responsibility
Accepted
Monte Cresta
Upper Lock
Lower Lock
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TABLE 16
STATUS OF UNIMPROVED ROADS AND PAPER STREETS
IN THE SAN JUAN HILLS PLANNING AREA
Only
Dedication
Accepted
* Bartlett
Marsten *
Marburger
East Laurel
Alhambra
San Ardo
* Creek
Dedication
Rejected
Naughton
Green Court
*
Portions of these streets which were located outside of the City limits of the time of dedication {1926-27} are not dedicated.
Source: City of Belmont
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Potential Impacts. Under the proposed San Juan Hills Area Plan several policies regarding road development would restrict the extension of roadways in the planning area. The following policies would restrict road development:
o To protect natural features of Laurel Creek Canyon and Sugarloaf Mountain, development of the section of East Laurel Creek north of Marsten Avenue is discouraged (Policy 12a).
o Road development · which would result in minimal grading and vegetation remova 1 is promoted. to protect natura 1 features throughout San Juan Hills (Policy 9).
o Roads that pass through areas with critical geologic hazards will not be developed unless these hazards can be removed (Pol icy 7).
Bartlett Way, Naughton Avenue and Lower Lock Avenue could not be developed as through-roads and the geologically hazardous area that crosses Marburger Avenue would have to be removed under this policy. o Moderate geologic hazards cross portions of other paper streets in San Juan Hills. These geologic hazards would require mitigation before development could occur (Policy 8).
In order for the 1 ot merger/resubdi vision process to work in the areas with geologic hazards and steep slopes, participation by all landowners on the roadway would be necessary to ensure that access rights are not violated by development of cul-de-sacs instead of through streets. Where geologic hazards do not exist, or where the hazards can be mitigated, 1 andowners would be required to develop a design and financing plan for new road development prior to the issuance of building permits.
Given the above development constraints and potential resolutions to those constraints, road development would most likely occur as depicted in Figure 7. As shown, existing roads, including Marburger Avenue, Upper Lock Avenue and the southern part of Marsten Drive that connects to Christian Drive and Green Court, would be upgraded. Roads which traverse areas with severe geologic hazards, including Bartlett Way, Naughton Avenue and Lower Lock Avenue, could be developed up to, but not through the hazardous areas. Direct access to Ralston Avenue (westbound) would be developed at the Horse Ranch site. Alternative access would be provided via Christian Drive and Marsten Avenue. The northernmost part of Marsten Avenue would be developed as an emergency access road. It would require paving and would need to be gated at both ends. There is an eastern gate near the Marsten Avenue/East Laurel Creek junction, but no western gate.
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New road development standards presented in the Area Plan include minimizing the required right-of-way width and permitting narrower streets in hillside areas. Where streets are developed in steep areas, parking bays, rather than continuous street side parking is promoted; and permeable (gravel) paths rather than sidewalks are encouraged. These road standards together with the restricted development of road access would limit the negative environmental impacts of road development in the San Juan Hills planning area.
Full or partial development of some of the paper streets would require resolution of maintenance and dedication responsibilities particularly on Marsten Avenue, Bartlett Way, Naughton Avenue, and Marburger Avenue.
Mitigation Measures. The f o 11 owing measures are recommended to off set potential impacts resulting from implementation of the Area Plan:
1. The City should work with landowners to facilitate implementation of the density transfer program and the lot merger/resubdivision process through on-site studies and follow-up meetings.
2. To ensure adequate provision of emergency access to the Skymont area the City should accept road dedication with maintenance responsibilities for Marsten Avenue, as a gated, emergency access road. The City should ensure safe emergency access to all development in the planning area.
3. As Marburger Avenue is improved to City standards, the existing geologic hazard should be corrected to ensure safe year-round access.
4. In areas with no on-street parking, "no parking" signs should be installed and a rigorous enforcement program should be implemented.
5. Permeable paths in hillside areas should be designed to minimize maintenance requirements.
6. Roadway extensions in hillside areas should be required to be built prior to the issuance of building permits.
Schools
Setting. Two schools in the Belmont School District and one school in the Sequoia Union High School District serve the San Juan Hills planning area.
Fox Elementary School, located at 3100 Saint James Road, has a current enrollment of 420 students in kindergarten through fifth grades. Ralston Middle School, located at 2675 Ralston Avenue, has a current enrollment of 614 936
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students in sixth through eighth grades (Dr. Edward Battistini, Belmont School District, personal communication). Carlmont High School, located at San Carlos Avenue and Alameda De Las Pulgas is within the Sequoia Union High School District and has a current enrollment of 1,493 students in the ninth through twelfth grades (Dr. Robert Hunter, Sequoia Union High School District, personal communication).
Enrollment in the Belmont School District has decreased by half over the last five to six years and the schools are operating at well below capacity.
Along with changing demographics, the presence of several parochial and private schools in the area is responsible for declining enrollment in the Belmont schools (Dr. Edward Battistini, Belmont School District, personal communication).
Potential Impacts. At present, all of the schools in the Belmont School District and Sequoia Union School District have excess capacity and would be ab 1 e to serve future residents of the San Juan Hil 1 s area. Therefore, the proposed project would not have a significant impact on elementary or secondary schools in the project area.
Mitigation Measures. None are required.
Water Supply and Distribution
Setting. The Belmont City Water District provides water to the San Juan Hil 1 s area. Water is stored in two tanks: one tank is near Ra 1 ston Avenue and Green Court and has approximately 0.5 million gallons capacity; the other tank is in the Cipriani neighborhood near Oekoven and Lincoln Avenues and has approximately 1.7 million gallons capacity. Water mains currently exist in street right-of-ways. Individual lines connect residential units and fire hydrants to the mains (Warren Mitchell, Belmont City Water District, personal communication).
Potential Impacts. Since the Area Plan permits less development in the San Juan Hi 11 s than could occur under the existing Genera 1 Pl an, future demands on water supply, storage and distribution facilities would be less than would occur under the General Plan. Although water supply and storage capacity is adequate to serve buildout of the planning area under the proposed Area Plan, water mains might require extension into currently undeveloped areas. Connecting lines would also have to be installed to serve individual units. Landowners benefiting from infrastructure improvements would be required to finance installation of new water lines, and if necessary, extension of existing water mains.
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Mitigation Measures. None are required.
Sewage Collection and Treatment
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Setting. The current sewage collection system in the planning area operates by a combination of pumping stations and gravity flow. Sewage in the San Juan Hills area is collected at the pump station on East Laurel Creek Road and pumped through a force main on San Juan Boulevard to Ra 1 ston Avenue and Cipriani Boulevard. The pump station was upgraded in 1979 and is sized to accommodate sewage generated by buildout of the planning area. From the pump station, gravity fl ow carries sewage to the South Bayside System Authority (SBSA). Trunk lines now exist in the planning area and are adequate to serve buildout needs. However, collection lines connecting development to trunk lines in undeveloped areas would need to be installed {John Hopkins, City of Belmont, personal communication).
The South Bayside System Authority, located in Redwood City, currently provides sewage treatment services for the planning area. SBSA also provides service to Redwood City and San Carlos. SBSA's Redwood City Treatment Plant is currently undergoing expansion which will increase its capacity by two mill ion gallons per day (mgd) for a total treatment capacity of 26 mgd (Ed Heller, South Bayside System Authority, personal communication).
The City of Belmont currently contributes 2 mgd to the sewage treatment system and has been allocated 2.3 mgd. If necessary, the City can purchase additional sewage treatment services beyond the 0.3 mill ion gpd of excess capacity that is currently allocated to it (John Hopkins, City of Belmont, personal communication).
Potential Impacts. Development under the proposed Area Pl an would be 1 ess than under the existing General Pl an. The ref ore, demands for sewage treatment facilities would be 1 ess than would occur with buil dout under the General Plan.
Development of the San Juan Hills area under the proposed Area Plan would not significantly increase the demand for sewage treatment facilities.
However, property owners would be required to finance i nsta 11 at ion of sewer lines to connect new development with existing trunk lines. New sewer lines would be required to be located in roadway rights-of-way for ease of maintenance.
Mitigation Measures. None are required.
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ENERGY CONSERVATION
Setting
The majority of the existing residential development in the San Juan Hills planning area is located on three gently sloping plateaus which are separated by two steep intervening canyons, Laurel Creek Canyon and San Juan Canyon. The plateau areas are sporadically vegetated with native and landscape species allowing for filtered sunlight throughout most of the area.
Approximately half of the canyon areas are vegetated with annual grassland and brushland, however solar access in these areas is restricted due to the northfacing exposure of the slopes. Climatic condition� in the City of Belmont are discussed in the Climate and Air Quality section of this EIR.
Energy consumption in the San Juan Hills planning area is associated with the residential development in the Skymont, Plateau and Cipriani neighborhoods. Natural gas and electricity service in the planing area is provided by Pacific Gas and Electric Company (PG&E). Electrical service is distributed by overhead lines and gas service is provided by three-inch mains located along improved roadways of the San Juan Hills planning area. The only improved roadway in the planning area that is currently without gas or electric service is the northern portion of the Bishop Road loop.
The California Energy Resources Conservation and Development Commission (Energy Commission) was created under the Warren/Alquist State Energy Resources Conservation and Development Act (1974). The Warren/Alquist Act requires that new residential building efficiency standards: (I) save energy, (2) include performance as well as prescriptive compliance approaches, (3) be cost effective when taken in their entirety and when amortized over the economic life of the structure, and (4) include an option of using passive or semi-passive thermal system design, such as daylighting and thermal mass.
Mandatory features and devices of the Commission's energy efficiency standards for new residential buildings include air leakage control, glazing, insulation, and heating/cooling/ventilation design requirements. State energy policy also includes measures to reduce regional vehicle miles of travel by automobiles and associated gasoline consumption.
Requirements for heating and cooling systems are based on a measurement of heating degree days. Heating degree days measure the tot a 1 number of degrees below 6S°F that mean temperatures fa 11. The heating degree days measurement is used to estimate fuel consumption and to specify the nominal annual heating load for a building. It is also used to determine the allowable heat flow rate and level of required insulation throughout a building. The Energy Code establishes standards for i nsul at ion of wa 11 s, 939
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ceilings, floors, pipes and ducts and places limitations on the amount and type of glazing based on the number of heating degree days in a locality. The City of San Mateo, which has similar climatic conditions to the planning area, has an average of 2,655 heating degree days per year. Based on this, design standards for energy conservation in residential uses are set at 36°F in the winter and 87°F in the summer.
Energy conservation standards for new resident i a 1 buildings are established in Title 24 of the California Administrative Code, and are enforced by local building departments through the building permit process.
Potential Impacts
Development under the proposed San Juan Hills Area Plan would result in fewer residential units in the planning area than buildout under the General Pl an. Si nee energy consumption corresponds with the amount of development, buildout under the Area Plan would have less of an impact on energy resources than buildout under the General Plan.
Initial energy consumption increases due to development in the planning area would result from site clearing and grading, construction of access roads and utilities, and the indirect energy consumption necessary for fuel and building materials. Long-term energy impacts would result from heating and cooling of residential units, water heating, general gas and electrical household needs, and fuel for transportation. Energy consumption must conform to the conservation requirements set by Title 24 of the California Administrative Code.
Construction of the future residential uses under the proposed Area Plan would entail use of heavy earth-moving and grading equipment, electric and pneumatic tools, and various other energy consuming equipment. Diesel fuel requirements would be dependent upon the amount of fill and/or excavation of material, the trip distance and fuel consumption rate. Additional energy would also be required for construction of access roads to development.
Development in the planning area would require the extension of overhead electrical lines and three-inch gas mains to the residential units. PG&E anticipates no problems in providing additional service to the planning area (Carol Silva, PG&E, personal communication).
Energy consumption in residential dwellings is largely dependent upon design components including building materials, alignment of structure, type of energy source (gas, electric, solar), and size of the structure. Because specific site development plans have not been determined for buildout of the 940
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planning area, it is not possible to calculate average annual energy consumption for the future deve 1 opment in the San Juan Hi 11 s. However, in conformance with fixed budget requirements of Tit 1 e 24 of the Ca 1 if orn i a Administrative Code and assuming no air conditiy
ning, residential energy
consumption would be a maximum of about 12,300 BTU per square foot per year for space heating and 20,800 BTU per residential unit per year for water heating (Bob Dunn, California Energy Commission, personal communication}.
As described in the Traffic and Circulation section of this EIR, potential development in the planning area would result in an additional 3,720 two-way trips per day in the San Juan Hills area. Utilizing an estimated trip 1 ength of 6. 2 mil es and a fue 1 consumption rate of 18 mil es per ga 11 on for autos (Lee Stamets, California Energy Commission, personal communication}, the full buildout of the planning area would result in an additional daily fuel consumption of approximately 1,280 gallons of gasoline.
Mitigation Measures
Three basic approaches to energy conservation can be integrated into new deve 1 opment: siting and ori en tat ion of deve 1 opment in re 1 at ion to 1 oca 1 and c 1 i mat i c conditions, use of a 1 tern at i ve energy sources, and use of energyefficient construction methods. Si nee the project is an Area Pl an and does not include specific plans for future development, site-specific energy conservation design recommendations cannot be formulated. However, the following general guidelines are recommended to offset potential adverse impacts related to energy consumption.
The following measure is required by State policy:
1. The project must comply with Title 24 Energy Conservation Standards of the California Administrative Code. Minimum requirements set by Title 24 include wall and ceiling insulation, infiltration control, properly sized space conditioning and hot water equipment, setback thermostats, requirements governing shower heads and faucets, and switching devices to control lighting. Future residential development must also meet the fixed budget requirements of Title 24 concerning space and water heating energy consumption.
lFor buildings, the basic unit of heat is the British Thermal Unit (BTU}.
One BTU is the amount of heat required to raise one pound of water (about one pint) one degree Fahrenheit at one standard atmosphere of pressure. 941
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The following additional measures are recommended to offset potential adverse effects:
2. The City should require the property owners benefiting from infrastructure extensions to be financially responsible for all gas and electrical extensions in the planning area.
3. The City should encourage energy-efficient building designs in the San Juan Hills area. Possible measures which could be incorporated into building design include:
o Aligning residential structures along an east-west or northwest-southeast axis to face as near to south or
southwest as possible in order to gain maximum solar
exposure.
o Landscaping with dee i duo us trees to pro vi de a windbreak and shade during the summer while providing direct
sunlight exposure during the winter. Coniferous trees
should be used for year-round sun shading and windbreaks. o Building designs which allow for natural ventilation
during warm periods and take advantage of incident solar insulation during the winter.
o Use of passive and/or active solar water and space heating systems.
4. Operation of construction equipment should be managed to avoid unnecessary fue 1 use. The amount of grading should be kept to a minimum.
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TOPICAL ISSUES AND IMPACT OVERVIEW
EFFECTS FOUND NOT TO BE SIGNIFICANT
The following potential impacts of the proposed San Juan Hills Area Plan and buildout under the Area Plan have been determined to be insignificant:
Land Use. Implementation of development under the Area Plan would result in a redistribution of development potential. Overall, potential buildout in the planning area would be decreased, with a slight increase in the amount of development permitted in the Laurel Creek Canyon subarea and a marked decrease in development in the Bartlett Avenue subarea. The restrictive Floor Area Ratios (FAR) instituted in the Area Plan would strictly limit development on very small and/or geologically hazardous lots. These factors would result in a lesser level of impact than would occur with development under the General Plan as the amount and location of development would be premised on environmental constraints.
Public Services. Development in the planning area would have no adverse impact on police or fire protection services or schools. There would be no difficulty in providing water and sewer service to the project site.
Implementation of the Area Plan would include provisions to upgrade many of the unimproved roadways in the planning area.
Traffic and Circulation. Project-generated traffic would not produce significant peak hour impacts at any analyzed intersections. Existing intersection p.m. peak hour level of service designations would not change.
Air Quality. Air quality emissions generated by buildout of the planning area would not exceed State or Federal air quality emission standards.
Noise. Deve 1 opment of the p 1 ann i ng area would have an ins i gn i fi cant impact on existing noise levels.
Energy Conservation. Through the imp 1 ementat ion of Tit 1 e 24 Energy Conservation Standards, energy consumption associated with buildout under the Area Plan would be significantly reduced.
POTENTIALLY SIGNIFICANT EFFECTS SUBJECT TO MITIGATION
The following potentially significant impacts of the San Juan Hills Area Pl an and development under the Area Pl an could be subjected to mitigative measures sufficient to reduce them to a level of insignificance:
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Geology and Soils. Development in areas located on or immediately downslope of potentially unstable slopes would pose a potentially significant hazard to human safety. Development, if improperly designed, could also increase landslide risks by altering drainage patterns, undercutting the bases of slopes, or loading the tops of slopes. These impacts could be reduced through the implementation of the geologic hazard policy map and mitigation measures including retaining walls, diversion structures, partial slope excavation and drainage terraces.
Hydrology. Buildout in the planning area would significantly increase the amount of impervious surface in the Laurel Creek watershed and the peak fl ow at the mouth of East Laure 1 Creek. Increased runoff could result in increased bank erosion and bed sedimentation, trigger landslides, and impact new structures through inadequately designed uphill drainage systems.
Localized storm runoff impacts could be reduced to a level of insignificance through implementation of improvements and policies recommended by the Storm Drainage Task Force and the San Juan Hil 1 s Area Pl an. Downstream impacts could be reduced through implementation of measures to reduce potential erosion and sediment loads and by retaining storm runoff in upstream locations during peak periods.
Vegetation and Wildlife. Buildout of the planning area could result in the significant removal of annual grassland, chaparral, mixed evergreen woodland and riparian woodland and their respective habitat types. Impacts to vegetation and wildlife would be reduced through the implementation of policies recommended in the San Juan Hills Area Plan, by negotiating any necessary streambed alteration agreements, and by planting native species for revegetation and landscaping purposes.
Visual Quality. Development of the planning area would alter the visual quality of the undeveloped portions of the San Juan Hills area, particularly in the Laurel Creek Canyon subarea. Extensive grading, removal of vegetation and 1 oss of open space would a 1 so alter the character of the area. Visual impacts could be reduced through the implementation of policies recommended in the Area Plan, establishing additional design review standards and requiring new residential development in the planning area to undergo design review, and by revegetation with native plant species.
Traffic and Circulation. With buildout of the planning area, traffic volumes would significantly increase at several intersections. Existing traffic safety concerns in the planning area would increase and the increased traffic would produce a measurable impact on some residents in the area.
These impacts could be reduced to a level of insignificance by implementing measures recommended in the Traffic and Circulation section of this EIR. 944
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UNAVOIDABLE SIGNIFICANT ADVERSE EFFECTS
There would be no direct unavoidable adverse effects due to the San Juan Hills Area Plan that could not be mitigated. However, the following significant adverse impact would occur as a result of buildout under the proposed Area Plan in conjunction with buildout of cumulative projects in the area and could not be completely mitigated:
Traffic. The incremental increase in traffic volumes resulting from buildou� under the Area Plan in addition to increased traffic resulting from cumulative projects would result in 1 eve 1 of service F operations at the Ralston Avenue/El Camino Real intersection. Traffic volumes at the intersection would exceed the theoretical capacity of the intersection by nine percent during the p.m. peak hour period. Although development under the Area Plan would only utilize one percent of the intersection's capacity, the Downtown Traffic Study {Hopper, 1985) indicates that there are no effective mitigations which would increase capacity at the intersection to accommodate cumulative traffic volumes. Therefore, the contribution to cumulative traffic impacts at this intersection resulting from development under the Area Plan is considered an unavoidable adverse effect.
IRREVERSIBLE ENVIRONMENTAL CHANGES
Potent i a 1 resident i a 1 bu i1 dout of the p 1 ann i ng area under the San Juan Hills Area Plan would preclude any future or alternative uses of the planning area. However, compatible alternative uses of the area are severely limited due to the close proximity of existing residential development in the planning area. An irrevocable commitment of financial resources, energy, raw materials and labor would be associated with development of the planning area.
Construction of development in the planning area would result in the removal of open space and wildlife habitat and would result in an irreversible alteration of the existing contours and slopes through mitigation of landslide hazards. Although the area has already been significantly altered from previous residential development, grading, slide retention structures and landscaping would result in a greater change in the natural condition of the undeveloped portions of the planning area.
Additional environmental alterations which would accompany development include increased population, surface runoff, traffic volumes and alteration of views.
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THE RELATIONSHIP BETWEEN LOCAL SHORT-TERM USES OF THE ENVIRONMENT AND THE
MAINTENANCE AND ENHANCEMENT OF LONG-TERM PRODUCTIVITY
Development of the planning area under the San Juan Hills Area Plan would result in a further extension of residential development within the area. It would result in a further loss of open space and would give the area a more urban character. Slope stabi 1 i zat ion measures, storm drainage improvements and revegetation of the area would result in a beneficial reduction in geologic and hydrologic hazards. However, significant site alteration would occur from grading, landscaping, diversion structures and slope stability activities including recompaction and installation of retaining walls. Such activities would permanently alter the natural landform and vegetation on the undeveloped portions of the planning area.
Further population growth in the area would generate public revenues but would contribute to degradation of water quality in East Laurel Creek and Laurel Creek from increased traffic, urban runoff, and a greater potential for erosion and landslides. Development would also permanently change existing vegetation and wildlife habitats.
Development in the San Juan Hills planning area under the Area Plan would restrict the number of permitted roadway extensions in the area. This would have a beneficial impact by preventing road construction in geologically hazardous areas and minimizing vegetation removal and grading.
Additional growth-inducing and cumulative impacts that would result from imp 1 ementat ion of the proposed project are described be 1 ow. It should be noted that implementation of the Area Plan would reduce the extent of environmental impacts resulting from development relative to the existing General Plan as the amount and location of development would be premised on environmental constraints. Under the Area Plan, development would be more condensed, the total number of permitted units would be reduced, and development would be confined to geologically stable areas.
CUMULATIVE IMPACTS
The long-term, cumulative impacts of implementation of the San Juan Hills Area Plan would result from development of approximately 372 residential units during the twenty-year timeframe of the Plan. Many of the impacts described in the Environmental Setting, Potential Impacts, and Mitigation Measures section of this EIR can be considered cumulative impacts because they would not be created by a single project, but rather, by area-wide development over a long period of time. Since residential development in the San Juan Hills 946
136
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would be located throughout the 1,000-acre planning area and the construction would be phased over time, localized cumulative impacts would be minimized.
Other proposed, pending or approved projects in the vicinity of the San Juan Hills area are comprised primarily of residential infill and professional office and retail space developments. The following projects are located near the planning area and would contribute to cumulative impacts:
Project
Davis Drive Offices1 1050 El Camino Real
Safeway Expansion
Creekside Offices
Creekside Condominiums
Island Park
Belmont Hills Hospital
Expansion
Size
84,000 SF
8,136 SF
8,453 SF
47,100 SF
18 units
Mixed Uses
Undetermined
Location
Davis Drive
1050 El Camino Real
El Camino Real at Emmett
1070 Sixth
O'Neill at Sunnyslope
Marine World Parkway
Ralston east of Chula Vista
Cumulative traffic impacts could result from additional vehicles added to local roadways. As discussed in the Traffic and Circulation section of this EIR, cumulative projects would generate a total of approximately 3,245 two-way evening peak hour trips. Significant impacts to intersection operations would result at the Ralston Avenue intersections with Belmont Canyon Road, Cipriani Boulevard, and El Camino Real. (See Traffic and Circulation section of this EIR.)
The 1 ow density resident i a 1 deve 1 opment permitted by the proposed Area Plan would not create emissions in sufficient quantity to threaten air quality standards. However, together with the incremental emissions of other development in the Bay Area, the project would contribute to the air basin's inability to meet clean air standards. The 3,720 vehicle trips per day generated by buildout of the San Juan Hills area would have a negligible local air quality impact, but would contribute to cumulative regional air quality impacts.
Construction-related cumulative air quality impacts could result from construction of the 372 residential units in the San Juan Hills area and the above projects in the vicinity. Dust generated by ground-clearing and lrhe 1050 El Camino Real project includes the demolition of an existing structure, resulting in a net increase in floor area of approximately 5,500 square feet.
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excavation and diesel exhausts from heavy equipment could impact regional air quality. Construction impacts would be temporary and could be reduced by implementation of mitigation measures recommended in the Climate and Air Quality section of this EIR.
When development under the Area Plan is considered with other proposed/approved developments in the area, cumulative impacts on public services and utilities may result. New water storage and distribution facilities, sewage collection and treatment facilities and additional police and fire protection personnel and equipment may be necessary to accommodate future cumulative deve 1 opment. Oeve 1 opment fees and increased property tax revenues generated by new developments would help to offset the costs of required expansions.
GROWTH-INDUCING IMPACTS
Potential future development under the Area Plan would be 26 percent less than that permitted under the existing Genera 1 Pl an. Al though the over a 11 1 evel of planned development would decrease under the proposed Area Pl an, adoption of the Area Plan and its implementing ordinances would make development more possible by providing mechanisms by which landowners of parcels with steep slopes or highly constrained access can transfer their deve 1 opment rights to more deve l opab 1 e pa rce 1 s. Therefore, adopt ion of the Area Plan could result in a higher level of development in the San Juan Hills (particularly in the short-term) than would occur under the existing General Plan.
To the extent that development under the Area Pl an is accompanied by roadway and service extensions, the project may open up future opportunities for development in areas which are presently considered inaccessible. The proposed Area Plan specifically addresses potential inducement of future development on nearby Sugarloaf Mountain and attempts to prevent such growth inducement by requiring an open space buff er between deve 1 opment in Laure 1 Creek Canyon and the mountain, and by strictly 1 imiting development in the canyon area.
ALTERNATIVES
A ful 1 range of alternatives to the proposed Area Pl an are discussed below, including the CEQA-mandated "No Project" alternative and two alternatives assessing potential development which could occur under the Area Plan if less restrictive and more restrictive slope density formulas were used. The alternative slope density formulas were developed by the San Juan Committee and were considered in the development of the Area Plan. The more 948
138
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restrictive formula was intended to result in larger minimum lot sizes in the planning area. The less restrictive formula was intended to permit development at higher densities, particularly in areas where lot merging and resubdivision could successfully occur. The more restrictive alternative was intended to result in overall lower densities of development throughout the planning area.
No Project Alternative. The No Project Alternative implies that the Area Plan would not be adopted and the existing policies of the General Plan would govern future deve 1 opment in the San Juan Hi 11 s p 1 ann i ng area. Under this alternative, the General Plan land use designations (Figure 8) would remain.
Under this alternative, a total of 604 units could be developed, with one unit per lot permitted throughout the project area (see Table 17).
Under the No Project Alternative, a greater level of environmental impacts would be expected to occur than under the proposed Area Plan.
Residential development at densities and in locations permitted by the General Plan would result in greater exposure to geologic hazards and potentially greater hydrologic impacts. The Area Plan.policies promoting preservation of open space for wildlife and aesthetic purposes would not be implemented and habitat and visual quality would be expected to decrease. The higher levels of development permitted by the No Project Alternative would result in higher traffic volumes than under the Area Plan, and consequently, greater air quality impacts and higher noise levels in the planning area. The demand for public services, such as fire and police protection, water and sewer, and.road maintenance would also be greater under the No Project Alternative than under the Area Plan.
Less Restrictive Alternative. This alternative would involve implementation of the Area Plan, but with a less restrictive slope density formula than proposed. A less restrictive slope density formula table is included in Appendix B. Under the Less Restrictive Alternative, approximately 455 residential units could be built in the planning area. This is 22 percent more development than would be permitted under the proposed Area Plan and 10 percent less than could be developed under the existing General Plan.
Table 17 shows the distribution of units by subarea under this alternative. As shown, 35 to 40 percent more development would occur in the Bartlett and Laurel Creek Canyon subareas under the Less Restrictive A 1 tern at i ve than under the proposed Area Pl an. Deve 1 opment in the other subareas would be similar to that permitted by the Area Plan. 949
139
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TABLE 17
NUMBER OF UNITS PERMITTED BY
ALTERNATIVE SLOPE DENSITY FORMULAS
Less More
No Project Proposed Restrictive Restrictive
Alternative Area Plan Alternative Alternative
Green Court 12 6 6 6
Naughton 42 22 25 22
Bartlett 143 28 43 25
Marsten 15 6 7 6
Marburger 35 17 18 17
Lower Lock 28 15 15 15
Upper Lock 13 6 6 5
San Arda Way 12 8 8 8
Alhambra 42 17 17 17
Monte Cresta 48 35 35 35
Laurel Creek Canyon 67 86 142 63
Laurel Creek Road 10 6 6 6
Marburger 11 6 8 6
San Juan Canyon 7 3 3 3
Ralston Frontage 14 6 11 6
Cipriani -i nfi 11 70 70 70 70
Pl ateau-i nfil 1 35 � 35 35
Total 604 372 455 345
Source: City of Belmont
950
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PERSONS PARTICIPATING IN REPORT PREPARATION
Larry Seeman Associates, Inc.
Elizabeth H. Tyler, AICP, Project Manager
Linda Ruffing, Assistant Project Manager
Anne Bikle, Environmental Analyst
Marie Strassburger, Environmental Analyst
Hans Giroux, Air Quality and Noise
T.J. Trimbur, Graphic Artist
Goodrich Traffic Group
Mark Crane, P.E., Traffic and Circulation
Rogers/Pacific, Inc.
Robert Olshansky, Geology and Hydrology
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PERSONS AND AGENCIES CONTACTED DURING REPORT PREPARATION Dr. Edward Battistini, Belmont School District, Assistant Superintendent Elaine S. Costello, City of Belmont, Community Development Director Barry Cromartie, City of Belmont, Associate Planner
Don Davis, City of Belmont Police Department, Captain
Bob Dunn, California Energy Commission
Doug Fry, South County Fire Department, Captain
Madelyn Glickfeld, MJG Incorporated, Planning Consultant Ed Heller, South Bayside System Authority Sewage Treatment Plant George Homolka, CH2M Hill
John Hopkins, City of Belmont, Director of Public Works Dr. Robert Hunter, Sequoia Union High School, Superintendent Warren Mitchell, Belmont Water District, Manager
Adel Nepomuceno, City of Belmont, City Engineer
Joe Perucci, City of Belmont Police Department, Lieutenant Hank Schmidt, South County Fire Department, Fire Marshal Carol Silva, Pacific Gas and Electric Company, Mapping Department Lee Stamets, California Energy Commission
Daniel Vanderpriem, AICP, City of Belmont, Acting Community Development Director
Ted Wooster, California Department of Fish and Game, Environmental Services Supervisor
953
954
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REFERENCES
Association of Bay Area Governments, et al, 1982. 1982 Bay Area Air Quality Plan.
Bay Area Air Quality Management District, 1985. Air Quality and Urban Development - Guidelines.
Bolt, Beranek, and Newman, 1973. Fundamentals and Abatement of Highway Traffic Noise. Washington, D.C.
California Air Resources Board, Annual. Air Quality Data.
California Air Resources Board. Annual Air Quality Data.
California Air Resources Board, 1983. Air Quality Analysis Tools.
California Energy Commission, 1980. Regulations Establishing Energy Conservation Standards for New Residential Buildings.
California Natural Diversity Data Base, 1985. Plot Report Quad-Margin Number Summary.
CH2M Hill, 1986. Community Facilities District for Storm Drainage Improvements, Draft Engineer's Report for the City of Belmont.
City of Belmont, 1986. Draft San Juan Hills Area Plan.
City of Belmont, 1986. Growth Management Program.
City of Belmont, 1986. Revised Policies San Juan Hills Area Pl an.
City of Belmont, 1982. General Pl an.
City of Belmont, 1967. Zoning Ordinance.
Earth Metrics, Inc., 1986. Final Environmental Impact Report for the Proposed Belmont Hills Hospital Expansion.
Galloway, W. J. and T. J. Schultz, 1979. Noise Assessment Guidelines, U.S.
Department of Housing and Urban Development.
955
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. lsa
Institute of Transportation Engineering, 1982. Trip Generation Report. Third Edition.
Martin Carpenter Associates, 1982. San Juan Area Specific Pl an Resource Analysis and Plan Alternatives.
Transportation Reserach Board, 1985. Highway Capacity Manual.
Wieczorek, Gerald F., et al, 1985. Map Showina Slooe Stabilitv During Earthquakes in San Mateo County, California, USGS Mi see 11 aneous Investigation I-1257-E.
William Cotton and Associates, 1985. Geologic Hazards Analysis of the San Juan Canyon Study Area, Belmont, California.
Wi 11 i am Spangle and Associates, Inc. , 1982. Proposed Genera 1 Pl an City of Belmont.
U.S. Soil Conservation Service, 1970. Report and General Soil Map, San Mateo County, California.
956
APPENDIX A
INITIAL STUDY
· lsa
957
958
I. Bodcground
City of Belmont
INITIAL STUDY OF
ENVIRONMENTAL SIGNIFICANCE
I. Nome of Propcnent City of Belmont
2. Address and Phone Number of Proponent 1365 Fifth Avenue Belmont. CA 94002 - (415) 573-3409
Date of initial study 3. 7-14-86
4. Agency Requiring Checklist ____ ..;.;.. N A ________________ _ S. Nome of Proposal, if opplicoble San Juan Hil"ls Area Plan and associat�d general plan amendments.
II. Environmental l�ts
(Exp lonot ions of oll "yes" and "maybe" answers are required on attached sheeis.) I. Earth. Will the proposal result !n:
0. Unstable earth conditions or in changes
in geologic subs1n.ctures?
b. Oisrv;,f iCY\S, displocements, corT'l)oc:tion
or overcovering of the soil?
c. Cho,ge in fopog rophy or ground surface
relief features?
d. The destruction, covering or modification
of any unique geologic or physical features?
e. Any ircreose in wind or water erosion of
soils, either on or off the site?
f. Chcnges in deposition or erosion of beach
sends, or changes in siltation, deposition or
erosion which may modify the channel of a
river or stream or the bed of the ocean or
my boy, in Jet or lake?
Yes Maybe No
X
X
X
X
X
1.b. Additional residential development and soils repair will result in compaction and overcovering of soil in some areas. The degree of impact is not expected to be significant due to mitigating policies controlling height, bulk, and grading to accommodate build-out under t�e proposed plan.
1.C. Grading for roadways and homes will result in topographic changes. The degree of change will be mitigated to a non-significant level by policies and implementing standardswhich reduce the amount of grading and control.its design.
Policies to protect vegetation, creeks, and wildlife and encourage clustering will further mitigate grading impacts.
959
g. E,;:,osure of people or property to geologic hazards such as earthquakes, landslides, mudslides, ground failure, or similar hazcrds?
2. Air. Will the proposal result in:
a. Slbstontiol cir emissions or deterioration
of ambient air quality?
b. The creotion of objectionable odors?
c. Al1erotion of air movement, moisture, or
femperoture, or any change in climate,
either locolly or regionally?
3. Water. Will the proposal result in:
a. Changes in o..,rrents, « the course of direct ion of water movements, in either marine or fresh woters?
b. Chalges in obsorpt ion rotes, dro inoge patterns, a the rote end amount of surfoc:e runoff?
c. Alterations to the course or flow of flood
woters'?
d. Change in the amount of surface water in
criy water body?
e. Discharge into svrfoce waters, or in a,y
alteration of surfoce water quality, including but not limited to te"1)erature, dissolved oxygen or turbidity?
f. Alteration of the direction or rote of flow
of ground waters?
g. Chcnge in the quantity of ground waters,
either through direct odditions or withdrowols, or through interception of Cl"'I oquif er by cufs or excavations?
h. SubsfontioJ redu:tion in the amount of
wo1er otherwise avoiloble for public wa1er
supplies?
i. Exposure of people 0< property to water relofed hozords such as floodi� or tidol waves? lg. Project will reduce exposure to slope failure.
Yes �
X
·-
X
X
X
X
X
X
-X
X
X
__ x_
3b. Overcovering of ground will result in additional runoff, althought runoff will be less than that resulting from full development under the existing general plan. Additional storm drainage is mitigated by policies requiring site specific hydrologic reports, prohibition of development in some areas, and connection to and improvement of the existing storm drain system.
2 960
)
4a,b.
9a
4.d.
8. 4. Plait Life. Will the proposol result in:
a. Change in the diversity of species, er
n.,mber of cr,y species of plants (including
trees, shrubs, gross, crops, Cl'\d aquatic
plants)?
b. Redl.Ction of the numbers of a,y unique,
rare or endangered species of plants?
c. Introduction of new speeies of plants into
on creo, or in o barrier to the norma I
replenishment of existing species?
d. Reduc1ion in ocreoge of cr,y agricultural
crop?
5. Animal Life. Will the proposal result in:
a. Change in the diversity of species, or
numbers of any species of animals (birds,
land onimols including reptiles, fish a,d
shellfish, benthic orgcriisms or insects)?
b. Reduction of the rumbers of any unique,
rare or endangered species of a,imols?
c. lntrodu:tiCJ"l of new species of a,imols into
on oreo, or result in o barrier to the
migration or movement of o,imols?
d. Deterioration to existing fish or wildlife
habitat?
6. Noise. Will the proposal result in:
7. 8.
o. Increases in existing noise levels?
b. Exposure of people to severe noise levels?
Lig,t and Glore. Will the proposal produce
new light or glare?
Land Use. Wi II the proposal result in a substonf iol clterof ion of the present or planned land use of an areo?
9. Natural Resources. Will the proposof result in:
a. Increase in the rcfe of use of any natural
resources?
Project will aid protection of natural resources.
Yes �
-
X
X
No
X
X
X
X
X
X
.x
X
X
X
Some agriculturally designated land would be redesignated for residential use. No effect on crops is anticipated�
The project •will result in a substantial change to the planned land use, resulting in an overall reduction of build-out density. No significant impacts are associated with the density reductions.
3 961
b. Si.bstontiol depletion of t:rty nonrenewable
noturol resource?
10. Risk of Upset. Will the proposal inYOlve:
a. A risk of an explosion or the refease
of hazardous sub.stances (including, but not
limited to, oil, pesticides, chemicals or
rodiation) in the event of a, occident or
upset conditions?
b. Possible interference with a, emergency
response pla, or a, emergency evocvation
pla,?
11. Population. Will the proposal alter the location
distributic:n, density, or growth rcte of the
'
h.Jmcn populotic:n of a, areo?
12. Housing._ Will the propose I affect existing housing, or creofe o demand for addit ionol housing?
13. Tr3"'1spor1ation/Circulation. Will the proposal
• resu It in:
o. Cenerotio n of substontiol additional
vehicvlor movement?
b. Effects on existing parking facilities, or
de mend for new pori< ing?
c. Substontiol i"l)oct upon existing traispor1otion systems? • d. Alterations to present patterns of c:ireulotion or movement of people end/or goods? e. Afterotic:ns to waterborne, rail or air
traffic?
f. Increase in troffic hazards to motor
vehicles, bicyclists or pedestricns?
14. Pl.blic Services. Will the proposol hove a,
effect upor,, or result in o need for new or
oltered govemmentol services in a,y of the
foll owing oreas:
o. Fire protection?
b. Police protection?
c. Schools?
Yes
X
X
X
�
X
----
X
X
X
X
X
X
X
X
11. Project will affect the distribution of residential densitites. Some areas will gain in density; some will decline depending on use of density transfer. 13c. Will result in rerouting of some curiently unbuilt rights of way, when fully implemented. Degree of impact will be contingent upon specific means of plan implementation but is not expected to be substantial. San Juan Area intersection capacity impacts are projected to be insignificant. Attached Exhibit A provides a summary and back up calculations for intersection level of service (Los) impacts. No Los impacts are projected. A cumulatively significant impact will occur at the El Camino Real/Ralston Avenue intersection. (Page4) 962 14 a & b. Additional demand for fire protection and police services will not be significant. Policies to coordinate access and establish appropriate road standards will further mitigate impacts to emergency ·service provision.
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963
d. Paks or other recreotionol facilities?
e. I.A.ointenonce of p\.blic facilities, including
roods?
f. Other governmental services?
IS. Energy. Will the proposal resvlt in:
a. Use of substontiol amounts of fuel or energy?
b. Subs font iol increase in demond upon exis1-
ing sources of enetgy, or require the
development of new sources of energy?
16. Utilities. Will the proposer resurt in o need
for new systems, or svbstonticl olterotions to
the following utilities:
a. Power or natural gas?
b. Commvnicotions systems?
.c. Water ?
d. Sewer or septic tonks?
e. Storm water �roinoge?
f. Solid waste ond disposol?
17. Hurncr\ Health. Will the propose I result in:
a. Creation of ony heolth hazard or potential
heofth hazard (excluding mentol health)'?
b. Exposure of people to potential heolth
hazards?
18. Aesthetics. Wi II the proposal result in the
obstruction of ony scenic visto or view open to
the public, or will the proposal result in the
erection of on oestheticolly offensive site open
to public view?
I�. Recreation. Will the proposal result in on
impoc:1 upon the qvol_ity or qvon1ity of existing
recre<1tionol opportunities"?
20. Cultural Resources.
o. Will the proposal result in the alteration
of or the destruction of o prehistoric or
historic orchoeologicaJ site?
Yes Maybe
X
X
X
X
X
x·
X
;x
14e. Proposed policy is aimed at providing roadbeds in stable.areas only.
Current stability problems will be avoided in new road areas. 16e. Significant increases in storm water runoff may occur, thereby requiring alterations to the existing system.
5 964
b. Wi II the proposal result in odverse physical
or oe.s1he1 ic effects to a prehistoric or
historic building, strucrure, or object?
c. Docs the proposal have the potential to
covse a physical chcnge which would affect
unique e1mic cultural wlues?
d. Will the proposer restrict existing religious
or sacred uses within the potential i�t
areo?
21. Mcridatory Findings of Significanc::e.
a. Does the projec:1 hove the potential to
deg rode the quo lity of the envircnment
substont io lly reduce the hob itct of o fi�
or wildlife species, cOJse a fish or wildlife population to drop below self sustoining levels, threoten to eliminate o plant or animal community, reduce the
rumber or restrict the rcnge of a rore or
endongered plon1 or onimol or eliminate
important examples of the major periods
of Cclifornio his1ory or prehistory?
b. Does the project hove the potential to
ochieve short-term, to the �isodvof"\foge of
long-term, environmental gools? (A shortterm impoct on the environment is one which occvrs in o relatively brief, definitive
period of time while long-term impoc:ts
wi II �ndJre we II into the future.)
c. Does the project hove in-pocfs which ore
individually limited, buf cvmulotivefy considerable? (A project moy i"l)ocf on two or more seporo1e resources where the impoc:t
on each resource is re lot ively smell, but
where the effect of the totol of those
irrpoc: ts on the environment is sign if icont .)
d. Does the project have envircnmenfol effects
which will cause substontiol adverse effects
on human beings, either directly or indirectly?
111. Discussion of Environmental Evaluation
(See preceeding notations.)
� Maybe -No
- X
_.L,
X
X
X
X -
X
The project is intended to provide safe, all-weather access to areas previously subdivided: to encourage resubdivision in a manner more sensitive to terrain limitations; to help preserve natural vegetation, riparian, and topographic features; and to provide more environmentally sensitive development controls.
The significant impacts associated with this project are identified in items 13c. and 16e (Traffic and Storm Drainage).
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IV. Determination
On the basis of this initial evaluation:
I find· that the proposed project COULD NOT hove c significant effect on the environment, end o NEGATIVE DECLARATION will be prepared. J_-I I find that although the proposed project could hove o significant effect on the environment, there will not be o significant effect in th is case 1-1 beccuse the mitigation meosures described on on ottoched sheet have been added to the project. A NEGATIVE DECLARATION WJLL BE PREPARED.
I find the proposed project MAY hove o significant effect on the environ- I XX I ��:y �
:
4 :
n
1 ::IRONMENTAL IMPACT R�ORJ12J ____ _:
Dote Signature Dan Vanderpriem,
For City of Belmont
7 AICP
966
APPENDIX B
PROPOSED FLOOR AREA RATIOS
(SLOPE INTENSITY TABLE)
AND ALTERNATIVE SLOPE DENSITY FORMULAS
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968
PROfOSED CHANGES TO THE TLOOR AREA RATIO - Rl AREAS
]. Split slope categories further·
2. Flat FAR within slope categories
3. · Sq.ft. = WholP. building envelope minus enclosed · or roof decks
4. Mini•um house size 1000 sq .. ft. (lots with square
footage belo� this need t� be combined)
5. Maximum house size 3500 sq. ft. (lots with square
footage above this can only build to ■axi■um)
0-15% slope
Lo1 Size (sq. ft.)
4,000
4,500
5,000
s, soo'
6,000
10,000
12,000
16-30% slope
4,000
4,500
5,000
5,500
6,000
10,000
12,000
31-45% slope
4,000
4,500
5,000
5,500
6,000
10,000
12,000
45�+ slop�
4,000
4,500
5,000
5,500
6,000
10,000
12,000
FAR
� .. 4 0
.·4 0
.·4 0
.40
.40
.40
.40
.30
.30
.30
.30
. :rn
.30
.30
.25
.25
.25
.25
.25
.25
.25
.15
. 15
. 15
. 15
. 15
. 15
. l 5
House Size (sq.ft.)
1,600
1,800
2,000
2,200
2,400
4,000
4,800
1,200
l, 350
1,500
1,650
1,800
3,000
3,600
1,000
1,125
1,250
1,375
l, 500
2,500
3,000
600
675
750
825
900
1,500
1,800
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, . ... .
Average
Slope
0-9%
10%
11%
12%
13%
14%
15%
16%
17%
18%
19%
20%
21%
22A
23%
24%
25%
26%
27%
28%
29%
30%
3_1%
32%
33%
34%
35%
36%
37%
38%
39%
40%
41%
42%
43%
44%
45%+
ALTERNATIVE LESS RESTRICTIVE SLOPE DENSITY TABLE
TABLE OF ALLOWABLE DENSITY
Maximum
Dwelling Units
per net acre
7.26 6.70
6.22 5.73
. 5.25
4.84 4.44
4.07 3.72
:,.43
3.18 3.oo·
2.85 2. 71
2.58 2.46
2.35 2.25
2.15 2.05
1.94 1.85
1.74 1.63
1.52 1.41
1.30 1.21
1.21,
1.05 0.98
0.92 0.85
0.79 0.74
0.69 0.64
Minimum
Net Lot Size
(sq. ft.)
6,000
6,500
7,000
7,600
8,300
9,000
9,800
10,700
11,700
12,700
13,700
14,500
15,300"
16,100
16,900
17,700
18,500
19,400
20,300
21,300
22,400
23,600
25,100
26,800.
28,700
30,900
33,400
36,100
38,800
41,600
44,600
47,600
51,100
54,800
58,800
63,300
68,300
970
Average
Slope
0-9%
10%
11%
12%
13%
.14%
15%
16%
17%
18%
19%
20%
21%
22%
23%
24%
25%
26%
27%
28%
29%
30%
31%
32%
33%
34%
35%
36%
37%
38%
39%
40%
41%
42%
43%
44%
45%+
ALTERNATIVE MORE RESTRICTIVF SLOPE DENSITY TABLE
TABLE OF ALLOWABLE DENSITY
Maximum
Dwelling Units
•. · ·: per net acre
7.26 5.73
4.65 3.85
3.23 2.74
2.34 2.02
1.76 1·.·56
1.40 1.28
I.1.9
1.lI·
1.04 0.97
0.92 0.87
0.82 0.78
0.72 o.67
0.62 0.57
0.52 0.47
0.44 0.40
0.37 0.34
0.32 0.30
0.28 0.26
0.24 0.22
0.21 Minimum
Net Lot Size
(sq. ft.)
6,000
7,600
9,360
11,300
13,500
15,900
18,600
21,600
24,800
28,000
31,200
33,900
36,600
39,300
42,000
44,700
47,400
50,100
53,100
·56,100
60,100
64,900
70,500
. 76,900
84,100
92,100
100,100
108,900
117,700
126,500
136,100
145,700
156,900
168,900
180,900
193,700
210,500
971
I I
972
lsa
APPENDIX C
SPECIES LIST FOR SAN JUAN HILLS AREA
973
974
VEGETATION IN THE SAN JUAN HILLS
Compositae
Gnaphalium sp.
Baccharis pilularis
Achillea millefolium
Cirsium sp.
Artemisia californica
&. douglasiana
Holocarpha virqata
Centaurea solstitialis
Rhamnaceae
Rhamnus californica
Sambucus mexicana
Ceanothus sp.
Fagaceae
0uercus aqrifolia
0uercus sp.
Fabaceae
Vicia sp.
Cytisus sp.
Umbelliferae
Conium maculatum
Foeniculum vulqare
Hercleum lanatum
Pimpenella Anisum
Hippocastanaceae
Aesculus californica
Salicaceae
Salix sp.
Solanaceae
Solanum xantii var.
intermedium
Primulaceae
Anagallis arvensis
Coyote Brush
Yarrow
Thistle
California Sage
Mugwort
Tarweed
Yellow Star Thistle
Coffeeberry
Blue elderberry
Buckbrush
Coast Live Oak
Oaks
Vetch
Broom
Hemlock
Sweet Fennel
Cow Parsnip
Anise
Buckeye
Wil 1 ow
Nightshade
Scarlet Pimpernel
lsa
975
Aspidiaceae
Polystichum munitum
Pteridaceae
Pityrogramma triangularis
Pteridium aguilinum
Typhaceae
� latifolia
Caprifoliaceae
Lonicera hispidula
Lonicera sp.
Rosaceae
Heteromeles arbutifolia
Rosa sp.
Rubus parviflorus
Prunus sp.
Physocarpus capitatum
Osmaronia carastiformis
Saxifragaceae
Ribes sp.
Scrophulariaceae
Mimulus auranticus
Taxodiaceae
. Seguoiadendron giqanteum
Lauraceae
Umbellularia californica
Plantaginaceae
Plantaqo sp.
Labiatae
Satureia douglassi
Cruciferae
Raphanus sp.
Brassica sp.
Sword Fern
Golden-back Fern
Western Bracken Fern
Cat Tail
Honeysuckle
Honeysuckle
Toyon
Rose
Thimbleberry
Western Ninebark
Osoberry
Gooseberry
Sticky Monkey Flower
Redwood
California Bay
Plantain
Verba Buena
Wild Radish
Wild Mustard
lsa
976
Juncaceae
Juncus sp.
Cyperaceae
Cyperus sp.
Gramineae
Lolium sp.
Avena fatua
Bromus sp.
Festvca sp.
Phalaris sp.
Orchidaceae
Epipactis qigantea
Dipsacaceae
Dipsacus fullonum
Ranunculaceae
Thalictrum polycarpum
Ericaceae
Arbutus menziesii
Common Rush
Sedges
Rye
Wild Oat
Bromes
Fescue
Canarygrass
Stream Orchid
Fuller's Teasel
Meadow Rue
Madrone
lsa
977
978
OBSERVED WILDLIFE SPECIES
IN THE SAN JUAN HILLS
(December 4, 1986)
Mammals
Mule Deer Odocoileus hemionus
Coyote Canis latrans
Racoon Procyon later
Western Gray Squirrel Sciurus griseus
Amphibians
Birds
California Slender Salamander - Batrachoseps attenatus
Red-Tailed Hawk Buteo jamaicensis
Mourning Dove Zenaida macroura
Anna's Hummingbird Calypte anna
Common Flicker Colaptes auratus
Scrub Jay Aphelocoma coerulescens
Plain Titmouse Parus inornatus
Chestnut Backed Chickadee Parus refescens
Yellow-Rumped Warbler Pendroica coronata
Robin Turdus miqratorius
Brown Towhee Piplio fuscus
Purple Finch Carpodacus purpureus
Golden-Crowned Sparrow Zonotrichia atricapilla
Savanna Sparrow Passerculus sandwichensis
Hutton's Vireo Vireo huttoni
lsa
979
980
Mammals
POTENTIAL WILDLIFE SPECIES
IN THE SAN JUAN HILLS
Gray fox Urocyon cinereoarqenteus
Opossum Oidelphis virginiana
Striped skunk Meohitis mephitis
Dusky-footed woodrat Neotoma fuscipes
Botta's pocket gopher Thomomys bottae
Western harvest mouse Reithrodontomys megalotis
California vole Microtus californicus
Brush rabbit Sylvilagus bachmani
Ornate shrew Sorex ornatus
California ground squirrel Spermophilus beecheyi
California mouse Peromyscus californicus
Amphibians
Yellow-eyed salamander Ensatina ensatina xanthoptica
Arboreal salamander Aneides luqubris
Reptiles
Ring-necked snake Diadophis punctatus
Terrestrial garter snake Thamnoohis terrestris
Pacific gopher snake Pituophis melanoleucus catenifer
Kingsnake Lampropeltis getulus
Racer Coluber constrictor
Western rattlesnake Crotalus viridus
Western skink Eumeces skiltonianus
Northern alligator lizard Gerrhonotus coeruleus
American kestrel Falco sparverius
Turkey vulture Cathartes aura
California Quail Loohortyx californicus
Great horned owl Bubo virginianus
Acorn woodpecker Melanerpes formicivorous
Nuttall's woodpecker Picoides muttallii
Ash-throated flycatcher Myiarchus cinerascens
Western flycatcher Empidonax difficilis
Western meadowlark Sturnella neglecta
· lsa
981
Stellar's jay Cyanocitta stelleri
Bushtit Psaltriparus minimus
House wren Troglodytes aedon
Wrentit Chamaea fasciata
Winter wren Troglodytes troglodytes
Bewick's wren Thryomanos bewickii
Hermit thrush Catharus guttata
Solitary vireo Vireo solitarius
California thrasher Toxostoma redivium
Yellow warbler Dendroica petechia
Orange-crowned warbler Vermivora celata
Green-tailed towhee Pipilo chlorurus
Rufous-sided towhee Pipilo erythrophthalmus
House finch Carpodacus mexicanus
American goldfinch Carduelis tristis
Dark-eyed junco Junco hyemalis
Song sparrow Melospiza melodia
White crowned sparrow Zonotricha leucophrys
Grasshopper sparrow Ammodramus savannarum
Fox sparrow Passerella iliaca
lsa
982
APPENDIX D
TRAFFIC DATA
lsa
983
984
SIGNALIZED n,.'TERSECllONS 9-81
PLANNING APPLICATION WORKSHEETIntersection: RAL:STevtlel CAMINO /2EAL.. Date: 3/2-7,/'?S � . ·· 1 e:1 oo,JjR./Cf{- 'T/urFFIC..
Analyst: M-D C- C::,,/!..oVP TunePeriodAnalyzed:PM Pt:i"NL H/2__ Project No. _________ City /Statp·Bll,,.,,C. �0-M�...:..:::C:Yi��T---, �<!=-4�, __,;•------- SB lOTAL N-5 STREET
1IIJ I I
�o _) j '--240 I@
IQIID� J rrc
Z.01'.> �
@ 270 ')
z.70 �
_)loo !ail@
-,-,- 5
EB lOTAL \ '5'
[ID<fo�
EBLT =
WBTH =,300 -+(V
IJc0 I
WBII =
NBLT = t7o
SBTii ==SDO
l1o70 I
SBLT =24-0
EBIB- == 7...70 R
NBTii = (:So a
f 270 I. s: l�o t
:30D -1-z70 4@)� r'JO · · -+�
E-W CRITICAL N-5 CRITICAL
. ZiO�
boo@ � r----,
I�
�ZIO
( ..300 ®
4 ✓ -.300 ®
r'so
RALSTO'v\
@
170
13o0
&W�
, 1 ,.1cro � @
I I
NBlOTAL
MAXIMUM
SUM OF CRITICAL
VOLUMES
CAPACITY
LEVEL
0101,200
1,201 to t400
> 1,400
UNDER
NEAR
OVER
985
SIGNALIZED �"TEJlSEC'TJONS
PLANNING APPLICATION WORKSHEET
Intersection-@LS70k:7 /4U.M€!Jf! ./)€ L:4£ 1'0LG.ltS Date: /2 NO tJ ffo 9-81
I GooiJ.e1c1-1 TMFFtc �
Analyst: J.-1.QC G!louf> Tune Period Analyzed• f½ PE./IIC H/2 (S--{:.!ao.l'M) ProjectNo _________ Qty/State� Ba Ml?Y1r; C4,
SBlOTAL
I I ® .JJ\ � LfQ_ '-is
2<os
N-SSTREET
<'\, S{/0
� S '-10
1'=6 _ __.Jt
@) 57D--�)
@)57D-�
.._..:).)
._r-310
EBLT = t(oS NBLT ::2.25
J rn
WB TH =SiftJ f-zollltJe) SB ra -=JoS f10 �)
� �
WBLT ==310 � "SBLT "a=: .--BS __
MAXIMUM
SUM OF CRITICAL
VOLUMES
0101,200
. OR
EB ra. = 570 (1 R1ZJ2 . NB TH == l/-Z.O ($ e�� 1,201 to 1,400 �- 111�s I > 1,400
CAPACITY
LEVEL
UNDER
NEAR
OVER
986
SJGNAUZED IJi,.""nJlSE.CTIONS
PLANNING APPLICATION WORKSHEET
Intersection: f<A�\OV\ / C--H-P-.LS Tl AN DR.
' Date: \ Z. NO\J S'b
9-81
600.l)R,IC/-I TRAFFIC "'
Ana1yst: M t).C..... Gl!-o(.)f' · Tune Period Analyzed: Pk �eAde. HoLJL S-f..'oc Project No. _________ City /Stat�: ..... -8 ..... €.__U-1........._....;_0VI ___ �_,_ •..... r. ....... 1/3.........._· ______ _ 9D __ �
l4oJ@>7�o �
e±§)(y)7t,o -:)
C.H2-lSTIA.N
N-5 STREET
� St/-D Qg)
( $3S
c;-0.
RALStCN\
E-WSTREET
-,lr1 I
NB10IAL
_____ o;;;__=..i.....;::;..=-x...=.£-=C.....:.T __ C)=F>e.0:r Prcr I wf{ftJD1Ffe�"1r 6:f'2o:J'"" A-t:r L."'11-·--·�.0=- t..,CMt.(lt-,,1 EB LT = 'r ___ O __ NB LT = __ 0 __
WB TH -= S"'f() SBTii -30�1 @
1,� t
WB LT = -...0 __
EB T1:i
CJ
SBLT -=--
NB TH -= _...Q ___ _
71,0 -1-@13sl+30 -f@
E-W CRITICAL · N-S CRI�
,'as) � . ... -
OR
MAXIMUM
SUM OF CRITICAL
VOLUMES
0101,200
1,201 to 1,400
. > 1,400
CAPACITY
LEVEL
UNDER
NEAR.
OVER
987
SJGNAl.IZED n.nRSE.cnONS 9-81
PLANNING APPLICATION WORKSHEET
,I. ( HILLC�) -
Intersection: RALS/(211 //3Elf1CMI C'(IN .YCM eD Date: 12 IJO ti 8" (:, . IGOOD�ICH' -n2/lt="FIC . -,c,
Analyst: Hl>C-- G�"oP TrmePeriodAna1yzed:PM /Js/-/1:. flR. (.5-�:0t>f�, -
Project No __________ Oty /Stat�: ..... dic...G __ L_M _____ o-w_· _, ·--:r;.,....., _;a;C,4a.....:..,._. ______ _ SB10TAL
6EL.k-10ti-\T C4NYQ½
N-SSTREET
I I � _)l� 35 40 .
J.l
@�o ___ j
:�s;@ �70 =:,
� 10) l:?7D )
E-WSTREET
-,lr1- 1
NBlOTAL
... �n_-=--=--Pl/�6..::;;:�Tw..,;:::,iE_C....-..:.l ___ ��) rPS?oJ" /\LT ,,�J);FfE/lEJJr____ ,;.._.; _____ -----,1 D =GVMLJLA-nllt; EBLT = 8'D @
WBIB -=SBZ> ��
''"° 1·,@)
WBLT == 0 j
- >OR
EBTH · .. /o70 �
k,7o }}�9>
NBLT
,.
SBTH
SBLT
NB1H
=c
1 _o
CJ'
� 40 �'(OR a: 0
ltt-0 1J@
MAXIMUM
SUM OF CRITICAL
VOLUMES
0101,200
1,201 to 1,400
> 1,400
CAPACITY
LEVEL
UNDER
NEAR
OVER
988
SIGNALIZED INTER.SE.c-I1ONS
PLANNING APPLICATION WORKSHEET
Intersectionh?Ab.5:TOt-1 hem ANl- Date: t:3 Na ti f b
9-81
7 Goo.J)/2 ICH T/2JIFF1c_ �
Analyst: f1J). C.- G�ovP Trme Period Analyzed:13/"1 f'e-6(c ti 12. {s- �.'m, fl-t Project No. _________ City /Stat�: ... !3'-=&'L:..-.;;::;;.._�..;.;;;'CN/;....._.;....;..,f,-.......;;:C:....'."1.;...· _______ _ SBlOTAL
I I @ /l./-0 _)l"-135
®
lfil-36 -
@©
_)31.,,o
-1 -_-,_ 2
EBlOTAL \ ··
zoo
N-SSTREET
Jt;o 30 1?1.S
Jll
E-WSlJE(!"
55�
I S §__, f ,.zs
I I
NBlOTAL
t--,;ti,,.....:;............;...���--...-..c.
- , : PR();r A-LT / tvHEJJ JJJFF�ENT
-----===---..,;.__ = C-VMVLA ___ ___. rt vE..
EBLT
WBTH
WBLT
=3<,0 NB LT = lSS
==lf2.0 SBTH _30 .
l1<fl) I@ �
= 5D SBLT -= 135 @
OR OR
mra _ss ®
[fiQ]®
MAXIMUM
SUM OF CRITICAL
VOLUMES
o ro 1,200
1,201 to 1,400
> 1,400
CAPACITY
LEVEL
UNDER
NEAR
OVER
989
GTG
Trip Generation
Daily PM Peak Hour
--------------- -----------------------------
In Out
Units Rate Volume Rate Volume Rate Volume
Proposed Project 372 10 3720 .67 250 . 33 125
Alternate 1 455 10 4550 .67 305 .33 150
Alternate 2 345 10 3450 .67 230 . 33 115
Source: Institute of Transportation Engineers, "Trip Generation - An Informational Report," 1983 and Goodrich Traffic Group, based on correlation between peak hour traffic count on Christian Drive at Ralston Avenue and number·of existing residential units in the Skymont area. 24 990
lsa
RESPONSE TO COMMENTS
SAN JUAN HILLS AREA PLAN
ENVIRONMENTAL IMPACT REPORT
State Clearinghouse #86122320
PREPARED FOR
CITY OF BELMONT
JULY 1987
LSA ASSOCIATES, INC.
157 PARK PLACE
PT. RICHMOND, CA 94801
LSA #BEL601
991
992
1 COMMENTS RECEIVED ON THE DRAFT ENVIRONMENTAL IMPACT REPORT
INTRODUCTION
lsa
According to the State EIR Guidelines, a Final Environmental Impact Report consists of (1) the Draft EIR or revision thereof; (2) a 1 ist of persons, organizations, and public agencies comenting on the Draft EIR; (3) the comments and recomendations received on the Draft EIR, either verbatim or in summary; and (4) responses made to the significant environmental points raised by the comments. This document together with the Draft EIR constitutes the Final EIR.
This section of the Final EIR consists of a list of agencies, organizations, and individuals connnenting on the Draft EIR, followed by responses to the significant environmental points raised by the comments. The final section contains copies of the actual comments received and minutes of a Planning Commission hearing held on the Draft EIR.
Conrnenter
State Agencies
California Department of
Transportation
City of Belmont
Office of City Manager
Office of Planning and
Community Development
Private Organizations
Date
05/19/87
05/07/87
05/28/87
Cipriani Hills Neighborhood OS/26/87
Association
Cipriani Hills Neighborhood 05/28/87
Board Members
Response Page
3 3
4 7
16 Comment Page
39 38
39 41
44 993
2 lsa
Cormnenter Date Response Page Comment Page
Individuals
P.M. Melliar-Smith 05/29/87 19 46
David Charles Steiner 05/26/87 21 48
Public Hearings
City of Belmont Planning Commission 26 51
Hearing, May 5, 1987
Commissioner Green 26
Sal Pantano 27
P.M. Melliar-Smith 27
City of Belmont Planning Commission 28 54
Hearing, May 19, 1987
Mike McHugh 28
Lida Paetzke 29
Hartley Laughead 30
Commissioner Rianda 30
Commissioner Feierbach 31
Commissioner Green 33
Commissioner Collins 33
Commissioner Lawhern 33
Appendix
General Plan Text Amendments
994
I •
I :
I
I •
3 lsa
RESPONSES TO COMMENTS
This section presents the responses to the coments received on the Draft environmental Impact Report (DEIR). As required by the State EIR Guidelines, only responses to significant environmental points are included. For cross reference, all cormnents and responses are numbered sequentially. Comment and response numbers are keyed to the actual connnents contained in the last section of this report.
STATE AGENCIES
California Department of Transportation
Comment #1: Caltrans has reviewed the above-referenced project and has the following coment:
The Draft does not address the traffic impacts at the Ralston/Route 92 interchange. This impact should be discussed in the final EIR.
Response: Table 5 ("Roadway Impacts Due To Planning Area Buildout Traffic") on page 90 of the DEIR identifies traffic impacts on Route 92 east and west of Ralston Avenue. Traffic impacts were measured as an increase in existing PM peak hour traffic due to planning area buildout and expressed as a percentage of additional veMcles per hour. As shown in this table, there would be a two percent increase in the number of vehicles using Route 92 west of Ralston Avenue and a one percent increase in the number of vehicles using Route 92 east of Ralston Avenue as a result of planning area buildout.
CITY OF BELMONT
Ed Everett, City Manager
Comment #2: I also would like to change the wording in the Hydrology and Drainage section on page 61, item 2. I would rather we talk about doing the Study in "Consultation with" the City of San Mateo, not in "coordination with". The term "coordination" implies that San Mateo would have a say in any final recomendation regarding any mitigations·. I don't think we want to imply that. Certainly we will be talking to the City of San Mateo when we look at the EIR for the component of the Storm Drainage system.
Response: Mitigation Measure 12 in the Hydrology and Sumary sections of the DEIR on pages 61 and 7 of the DEIR, respectively, is changed to read (revised text is underlined):
995
4 lsa
"2. A storm drainage investigation should be conducted which addresses not only localized drainage in the San Juan Hills area, but also downstream effects. This study should evaluate potential increased peak flows in Laurel Creek and the potential for creekbank erosion and deposition downstream. The possibility of developing a series ·of check dams to capture silt and check erosion and/or developing retention basins to decrease peak flows should be addressed. This study should be prepared in consultation with the City of San Mateo. This study could be done as part of the recently authorized EIR on the San Juan Boulevard Stormdrains and the Downdrains in San Juan Canyon and East Laurel Creek." Comment #3: Traffic Section. The EIR has an existing V/C rate of . 97 {LOS of E) for the intersection of Ralston and El Camino. The revised draft of the final report of the Crain Study entitled "Transportation Planning Study for the Redwood Shores/IOI Corridor" has been looking at the same intersection. They came up with a .88 V/C ratio at the same intersection of Ralston and El Camino. I'm sure there are differences, depending on what day one does the traffic count, but I did want to make you aware that I am also looking at a draft document that deals with traffic in depth and at Ralston and El Camino Real the V/C ratios are different. It is not beyond possibility that they are both very accurate on the particular day(s) they were measured.
Response: The V/C ratio of .97 was derived from two sources; a traffic study completed for the City by Richard Hopper, and a previous EIR done for the City of Belmont on the Belmont Hills Hospital Expansion. The traffic analysis from these two studies determined similar V/C ratios for the Ralston Avenue and El Cami no Real intersection of about . 97. This 1 eve l of service was also supported by the Goodrich Traffic Group's visual observations of the intersection. One explanation for the wide range between the studies and observations of the intersection used in this EIR and that reported in the Crain Study could be that the Crain Study based its analysis on a particularly light traffic day.
Even if the level of service reported in the Crain Study were accurate, the unavoidable significant adverse effect at this intersection with cumulative traffic would remain. This is discussed on page 134 of the DEIR.
Planning and Community Development Department
Comment #4: Page 1, Introduction, second paragraph. There's a statement that when adopted, the Area Plan would become part of the Belmont General Plan and must be consistent. I think we had discussed that, as part of this project, we are proposing changes to the General Pl an to make sure that policies in the General Plan are consistent with the policies in the San Juan 996
5 lsa
Hills Area Pl an. I have attached a copy of the May 19, 1987 staff report which includes the amendments to the existing General Plan text. [Included as an attachment to the commentary letter.] I think this should be mentioned in the introduction and in the description of the project.
Response: The following text is added to the end of the second paragraph of the Introduction on page 1 of the DEIR:
"In addition, a number of General Plan text amendments are proposed to achieve consistency between the Area Pl an and the General Pl an. The proposed General Plan text amendments are included in Appendix B and are considered part of the project, as assessed in this EIR." The first sentence in the third paragraph on page 15 of the DEIR is revised to read as follows:
"The proposed project consists of an Area Plan, its implementing ordinances, and associated General Pl an text amendments, which provide specific pol i c i es to address the unique prob 1 ems and assets of the San Juan Hills area (City of Belmont, 1986)."
The following new text ; s added after the th; rd sentence in the third paragraph on page 15 of the DEIR:
"Associated General Plan text amendments are presented in Appendix B." The proposed Amendments to the General Plan text attached to the commenting letter are added to Appendix B of the EIR.
Comment #5: Page 10, Mitigation Measure #3, under Visual Quality and page 80, i tern #3, Mitigation Measures. Design revhw approva 1 for a 11 new single family residences in the San Juan is listed as a mitigation measure. I read the text of the EIR on visual quality and this mitigation is not justified in that section. I do not feel that design review approval of all new single family residences is necessary or practical. The implementing ordinances of the San Juan Hills Area Plan wil 1 set standards for the size, height, vegetation removal, and type of grading used for all new single family residences. These ordinances address the visual impacts discussed in the EIR.
Design review for all single family homes is, therefore, not necessary. It would be a burden to property owners and impractical, given the current City staffing.
Response: The conmenter 1s correct that the implementing ordinances of the San Juan Hills Area Plan will set standards for the size, height, 997
6 lsa
vegetation removal, and type of grading use for all new single family residences which would minimize the potential visual impacts in these areas.
However, the resultant development pattern on the receiver sites where the highest development density potential exists could still result in significant visual impacts. This mitigation is revised in Response to Comment #6 below.
Comment #6: Design Review for Receiver Sites. The major visual impact of residential development described in the EIR would be the development of the three (3) receiver sites if property owners choose to increase density through the density transfer program. Under our current ordinances, design review is required for all new development, except single family residences.
As an alternative to design review for all single family residences, design review could be required for development on receiver sites. This could be included in the implementing ordinances for density transfer. This would be an acceptable mitigation, if the intent of the mitigation proposing design review for single family residences was to address the visual problems pointed out in the EIR of increased development of receiver sites.
Response: Mitigation Measure #3 on page 10 and page 80 is changed to read as follows:
"3. As part of the implementing ordinances for the density transfer program, design review approval should be required for development of single-family residences on the proposed receiver sites. After a period of application of this design review, an evaluation of the review program should be conducted to determine if its implementation has resulted in a reduction in visual impacts."
Comment #7: Page 61, Hydrology and Drainage Mitigation Measures, number Z,. Line 4 -- The word "increased" should be added before creekbank erosion and deposition downstream.
Response: Mitigation Measure #2 on page 61 of the DEIR is revised to read as follows:
"2. A storm drainage investigation should be conducted which addresses not only localized drainage in the San Juan Hills area, but also downstream effects. The study should evaluate potential increased peak flows in Laurel Creek and the potential for increased creekbank erosion and deposition downstream. The possibility of developing a series of check dams to capture silt and check erosion and/or developing retention basins to decreas.e peak flows should be addressed. This study should be prepared in consultation with the City of San Mateo. This study could be done as part of the recently 998
7 lsa
authorized EIR on the San Juan Boulevard Stonndrains and the Downdrains in San Juan Canyon and East Laurel Creek.•
Comment #8: Line 8 -- The study should be done in consultation with the City of San Mateo, rather than in coordination. As the comments from the City Manager discuss, coordination implies equal participation by both groups.
This does not seem practical. On page 46, paragraph 4, under location of development the text states that under the Area Plan, the Bartlett area landowners would be encouraged to merge their lots. In fact, under the policies of the Area Plan, landowners would be required to merge their lots.
We are now currently writing a merger ordinance to require this. read:
Response: The third full paragraph on Page 46 of the DEIR is changed to •The greatest differences 1 n the location of future development would occur in the Bartlett and Laurel Creek Canyon subareas. Under the Area Plan, landowners in the Bartlett area would be required to merge their lots. There are 110 lots in the area with a potential for development of 143 units under the existing General Plan. However, there are only 20 separate ownerships so a great deal of lot merging could occur. The Area Plan would permit a maximum of 28 units in the Bartlett subarea. In the Laurel Creek Canyon subarea, which is currently unsubdivided, the Area Plan would permit development of 86 units, as opposed to the 67 under the General Plan."
PRIVATE ORGANIZATIONS
Cipriani Hills Neighborhood Association
Comment #9: We do not believe that ANY of the identified adverse effects will be reduced by mitigation to •a level of insignificance•, yet this claim is made repeatedly throughout the DEIR.
Response: Under Section 15382 of the California Environmental Quality Act (CEQA), "significant effect on the environment means a substantial, or potentially substantial, adverse change in any of the physical conditions within the area affected by the project including land, air, water, minerals, flora, fauna, ambient nohe, and objects of historic or aesthetic significance ••. " Detailed examples of significant effects can be found in Appendix G of the proposed action or project. Mitigation Measures, if followed, are capable of either fully or partially mitigating significant adverse effects, which 1 n turn results in the reduction of impacts to an insignificant level.
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The DEIR categorizes all potential impacts due to the project into three categories: effects found not to be significant, potent i a 11 y significant effects subject to mitigation, and unavoidable significant adverse effects (those that can not be mitigated). These are listed on pages 131-134 of the DEIR.
Comment #10: Permissive language is used throughout the DEIR which raises concerns that the mitigation measures proposed are opt i ona 1 and not mandatory; example, page 8, #3. "Native plant species SHOULD be used for revegetation •.•.••• "
Response: The Mitigation Measures in the DEIR are reconrnendations of the consultant, rather than requirements of the City of Belmont. Should the City decide to incorporate the Mitigation Measures as part of the San Juan Hil 1 s Area Plan, and its implementing ordinances, then the Plan and ordinances would need to be revised to incorporate the measures.
Comment #11: The DEIR proposes some mitigations that are contrary to established City Policy, i.e. extended hauling and construction hours, extended sidewalks in neighborhoods trying to retain a rural character, widening certain sections of Ralston Avenue.
Response: As stated on page 12 and on page 117 under Mitigation Measure #1 in the Noise section of the DEIR, construction activities would be limited to daytime hours--7 a.m. to 5 p.m. Monday through Friday. These proposed construction times are intended to limit hauling and construction hours, not to extend them. A shorter construction period (e.g., 9 a.m. to 4 p.m.) could also be adopted by the City.
Mitigation Measure #IO on page 96 of the DEIR recommends that pathways or sidewalks be constructed on at least one side of all new streets, as compared to the current City standard which requires that a sidewalk be provided on both sides of new roadways. The reco11111endation for sidewalks on at least one side of new streets is consistent with Policy 15a of the Draft San Juan Hills Area Plan, stating that, "Develop special hillside road improvement standards, including but not limited to right-of-way width, .•• sidewalks ... " which are "responsive to local physical conditions", and with Policy 15d, stating that, "Consider the use of paths and narrower sidewalks where this is an appropriate alternative to sidewalks in steep areas." The intent of these policies is to balance the beneficial effects of sidewalk development such as provision of safe pedestrian walkways, facilitation of storm drainage, and long-term protection and reinforcement of asphalt roadways with the potential change in neighborhood character and adverse visual impacts.
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Without the recommended traffic improvements along Ralston Avenue such as lengthening of existing left and right-turn 1 anes, unsafe and/or congested driving conditions would be created at the intersections identified in the DEIR, due to the traffic that would be generated from buildout in the San Juan Hills area. Widening of the roadway itself, other than at specific intersections, is not recommended in the EIR.
Comment #12: There is no discussion of the adverse effects on wildlife and vegetation during the actual construction process, which, according to the "Plan" is anticipated to be a twenty year period.
Response: Adverse effects on wildlife an vegetation during the construction process are discussed on pages 7-8 and on pages 67-70 of the DEIR. Adverse effects that were discussed on these pages include removal or alteration of native vegetation and the habitat types that such vegetation comprises, and the introduction of additional domestic animals into the planning area. Reco11111ended mitigation measures are identified on page 70 of the DEIR.
Comment # 13: The document assumes that cert a 1 n ordinances wi 11 be adopted to implement suggested mitigation measures, or as part of the San Juan Plan itself. Since there is no assurance that these ordinances WILL be adopted even if the San Juan Plan is approved, there must be some discussion of the consequences of adopting the •Plan" without such ordinances as •Heritage Trees", Geologic Hazards", •Lot Merger", •Density Transfer", etc .•• Response: Adoption of the San Juan Hills Area Plan will depend on the City approving the Plan. If the City decides to approve the Plan, the next step will be to adopt the Plan. Following adoption of the Plan, the City will be required to implement the policies contained within the Plan. Implementing the Plan will be accomplished through the development and adoption of ordinances. The City would not adopt the Plan unless they intended to implement the policies contained in the Plan, i.e., implementation of the Plan means developing and enforcing ordinances to carry out the Plan policies.
In accordance with CEQA, the DEIR includes the mandatory "No-Project" alternative. This alternative is a discussion of the consequences of not adopting the plan, and by association, the implementing ordinances as well; this discussion occurs on page 137 of the DEIR.
In addition, as noted on pages 1 and 2 of the DEIR (last sentence on page 1), as long as the implementing actions do not significantly differ from those discussed in this EIR, no further environmental review for the Area Plan or 1001
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implementing actions will be necessary. If the Area Plan or implementing actions do vary substantially from that assumed in the DEIR, further environmental review may be necessary.
Comment #14: There is no discussion of staff levels required to adequately monitor the construction process for strict enforcement of all proposed ordinances.
Response: Once the implementing ordfoances have been finalized and adopted, the City will decide the staffing levels that are needed to assure compliance with the ordinances.
Staffing requirements associated with the public services affected by the project are discussed on pages 118 to 126 of the DEIR.
Comment #15: Clarification is needed of the following sentence on page 137 (Growth-Inducing Impacts): "To the extent that development under the Area Plan is accompanied by roadway and service extensions, the project may open up future opportunities for development in areas which are presently considered inaccessible."
Response: An impact is considered growth-inducing if it would create conditions that are conducive for growth and development to occur in an area.
The San Juan Hills Area Plan would allow residential development to occur in an area that is currently undeveloped; roadway and service extensions would accompany such development. Oftentimes, service extensions into areas that were previously lacking services serves to foster growth. Although the San Juan Hills Area Plan would have a growth-inducing effect, it would also result in a limit on the total number of residential units that could be built in the planning area.
Comment #16: Financial impacts to the City of the proposed plan and the mitigations required are not addressed. If the financial impacts cannot be quantified this should be clearly stated.
Response: Financial impacts of adopting the San Juan Hills Area Plan are not expected to result in environmental impacts. According to Section 15131 of CEQA, "Economic or social information may be included in an EIR or may be presented in whatever form the agency desires. Economic or social effects of a project shall not be treated as significant effects of the environment ..• • It is the action of adopting and imp 1 ement i ng the Pl an, rather than the financial effects of the Plan upon the City, which constitute environmental impacts as analyzed in an EIR.
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Comment #17: Page 120 (Potential Impacts) "Improving and maintaining Marberger Avenue would provide year-around through access between the Plateau and Cipriani neighborhoods, thereby supplementing existing entry/exit points on Ralston Avenue. The proposed emergency access road linking Skymont to the rest of the San Juan Area would likewise increase access and police protection capabilities." Such a policy is not included anywhere in the proposed "Plan", and therefore should not be included in the DEIR.. What is proposed in the "Plan" is a gated emergency road for Fire ONLY on Marstens and the "Plan" does not address improvements on Marberger to connect Cipriani and Plateau. A connection for thru traffic between Cipriani and Plateau via Marberger shall be prohibited! The only emergency access between Cipriani and Plateau and Cipriani and Skymont shall be a gated emergency access 1 ike the one between San Carlos and Hallmark.
Response: Si nee the San Juan Hills Area Pl an contains no pol icy that specifically calls for either restricted access along Marburger Avenue, or for access improvements to Marburger Avenue, neither possibility would be precluded from occurring. As stated in the DEIR on page 121, emergency access along Marburger Avenue is often difficult to impossible during the winter months. If access improvements were to occur along Marburger Avenue, then emergency access would benefit. Under the Geologic Hazard Ordinance, the geologic hazard that exists on Marburger Avenue would have to be mitigated prior to access improvements.
Comment #18: Given the rate of breakdowns of the San Juan Pump Station and the recurring problems of odor emissions, we do not believe the Pump Station has the capacity to accommodate an increase of any amount (page 126).
Response: In 1983, there were severe and heavy rains which flooded East Laurel Creek and inundated the San Juan pump station. Since that time, the pump station has been operable. The City of Belmont Public Works Department regularly maintains the pump station and has provided emergency generators in the event of electrical failure, as well as security measures to ensure that the pump station is not tampered with. The other pump station, located at East Laurel Creek and Haskins Street, is currently being modified so that it will be compatible with emergency generators. The number of complaints regarding odors from the San Juan pump station have been minimal. The pump station house is outfitted with a device that minimizes the odoriferous gases (John Hopkins, City of Belmont, Department of Public Works).
Both stations were designed to acco11111odate development that would occur under buildout conditions. Since the San Juan Hills Area Plan would result in fewer units than the General Plan, the capacity of the sewage pump stations would be adequate to serve the proposed development levels outlined in the San 1003
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Juan Hills Area Plan (John Hopkins, City of Belmont, Department of Public Works).
Comment #19: The information presented in the DEIR indicates that the proposed "Plan" is not restrictive enough to protect the neighbors property, the native flora and fauna, the cumulative traffic and financial impacts to the community, the natural contours of the hillsides, and the geologic stability of specific areas.
Response: As stated on page 134 of the DEIR, the only significant adverse impact resulting from implementation of the San Juan Hills Area Plan that could not be mitigated is the cumulative increase in traffic volumes at the critical intersection of Ralston Avenue/El Camino Real.
As indicated in Table l of the DEIR, the San Juan Hills ARea Plan is more restrictive in terms of the number of units that could be built in the planning area than what the General Plan allows. In general, the lesser level of development allowed under the Area Plan can be expected to result in less intensive impacts than the level of development that would be allowed under the General Plan. A more restrictive alternative to the Plan is discussed on pages 140-141 of the DEIR.
Comment #20: Page 96. Additional mitigation ,:ieeded: Stop signs at ____ Cipriani and San Juan Canyon Road and Ponce Avenue and Cipriani to control traffic on Cipriani. Speed control BUMPS to replace Bots Dots on upper San Juan Canyon Road.
Response: Mitigation Measure #3 on page 95 and on page 11 of the DEIR states: "A priority list should be developed to provide stop signs on lower volume approaches to internal intersections. Signs should be installed first at high accident locations, and as funds permit, at all other locations." This Mitigation Measure addresses the need for stop signs at Cipriani and San Juan Canyon Road and at Ponce Avenue and San Juan Canyon Road. Speed bumps are norma 11 y used in areas where speeds of five to ten mil es per hour are needed, such as parking lots. Upper San Juan Canyon Road is a residential street; the legal speed limit on residential streets is 25 mph.
Comment #21: Page 69. Modification of Streambeds. The proposed Plan should not allow the modification of any streambeds.
Response: Pol icy 9 of the Natural Resources section of the San Juan Hills Area Plan states:
"Protect streams and creeks by:
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a. requiring that development, including roads, is set back from riparian corridors, and
b. preventing road alignments that cross creekbeds."
Implementation of these policies should minimize any disturbance of riparian areas and avoid the need for any streambed alteration agreements.
Cormnent #22: Page 25. Open Space Buffer. As a buffer is proposed as part of the Open Space Policy, the DEIR must list methods the City can utilize to acquire the open space buffer. At the very least, the DEIR should list potential funding sources, as well as organizations that could be utilized as resources to help find funds.
Response: The acquisition of an open space buffer between the San Juan Hnls and Sugarloaf Mountain will depend on the City of Belmont conducting negotiations with the City of San Mateo. The Midpeninsula Regional Open Space District could provide potential assistance during the negotiation process.
The following mitigation measure is added to page 47 of the DEIR:
"l:. The City of Belmont should work with the City of San Mateo and the Midpeninsula Regional Open Space District to ensure the presence of an open space buffer between the planning area and Sugarloaf Mountain."
Comment #23: Page 32. Heritage Tree Ordinance and Excavation Restrictions and Design Review Ordinance must be added to the list of proposed ordinances.
Response: Preservation of heritage trees is provided for under policy Sc of the Natural Resources section of the San Juan Hills Area Plan which states, "protect historic and scenic trees."
If the City deems it necessary to provide additional protection for trees, an ordinance to accomplish this can be developed.
The Geologic Hazards Ordinance, when completed, will provide excavation restrictions within the planning area.
Design review of future development in the planning area 1s expected to occur through the combined effect of the implementing ordinances of the San 1005
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Juan Hills Area Plan. The ordinances providing this function include a Geologic Hazard Ordinance, a Slope/Density Ordinance, a Merger Ordinance, Slope Intensity and Density Transfer Ordinances and development standards regarding grading, vegetation protection, and hillside roads. See also Comments #5 and #6 and the responses to these comments.
Comment #24: The DEIR shows conflicting statements regarding traffic impacts (pages 131-136).
Response: Considered by itself, additional traffic resulting from buildout of the Planning Area would not constitute a "significant effect".
However, when project-generated traffic is considered along with the cumulative traffic that would be generated due to other projects in the area, an "unavoidable adverse effect" would occur at the critical Ralston Avenue/El Camino Real intersection (page 134). The traffic impacts addressed on page 136 relate to the project-generated plus cumulative traffic.
Comment #25: Page 24. Natural Resources Preservation: Change the word "ensure" to "mandate" and "encourage" to "ensure".
Response: The text cited on page 24 of the DEIR is a synopsis, rather than a verbatim passage, of the goals and objectives of the San Juan Hills Area Plan. The City will determine the statutory language of this Plan.
Comment #26: Secondary Dwelling Units. The issue of secondary dwelling units is not addressed in the "Plan" or the DEIR. This issue must be addressed as it has the potential for a considerable increase in density over what h proposed. If a secondary dwelling unit, as allowed by State Law and City Ordinance, were to be added to each dwelling unit proposed for the San Juan Planning Area the additional negative impacts must be addressed. If Secondary Dwelling Units are not going to be allowed in the San Juan Planning Area the "Plan" must include this provision.
Response: It is likely that secondary dwelling units would be incapable of meeting the development standards contained in the various implementing ordinances of the San Juan Hi 11 s Area Pl an. The amendments to the Genera 1 Plan assuring compliance with the Area Plan (see attachment to City of Belmont Co11111unity Development Department co11111enting letter) are expected to have a similar effect in terms of discouraging development of secondary dwe 11 i ng units.
Co11111ent #27: Page 30. Road Improvements: Change the word "discourage" to "prohibited".
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Comment #28: The "Plan" should allow a minimum street width of 16 feet to further minimize excavation.
Response: A minimum street width of 16 feet is too narrow for passage of emergency vehicles.
Comment #29: The "Plan" must include provision for the preservation of the Eucalyptus trees on the "horse ranch" property.
Response: In order to make the horse ranch property a viable receiver site, protect the sensitive riparian areas in the canyon and create permanent open space areas at the sender sites, a portion of the eucalyptus trees on the horse ranch property are expected to be removed. Removal of these non-native species would not constitute a significant biological impact.
Comment #30: Undergrounding of utilities must be prohibited in areas where undergrounding would cause extensive disturbance of natural vegetation.
Response: Natural Resources Policies Sa through 8d of the San Juan Hills Area Plan protect natural vegetation through the following:
"a. minimize the removal of vegetation,
b. protect and restore vegetation which stabilizes soils and reduces surface water runoff, erosion and sedimentation,
c. protect historic and scenic trees, and
d. provide revegetation of all significant tree cover." Comment #31: Alternatives should include under "more restrictive" a 75% reduction in density.
Response: A more restrictive alternative is addressed on pages 140-141 of the DEIR. This more restrictive alternative would consist of approximately 27 units (seven percent) less than could occur under the proposed Area Plan.
It should be noted that the EIR assesses maximum buildout under the Area Plan. If the proposed lot merger and floor area ratio policies and implementing ordinances are successful, actual buildout under the Area Plan would be less than that assessed in the EIR. The EIR did not account for this potential reduction since the policies depend upon voluntary participation and there ts no guarantee that the reductions would be achieved. If the slope intensity and density transfer programs are successful, buildout under the 1007
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plan would consist of 275 to 300 units, rather than the 372 units shown in Table 1.
A more restrictive alternative than that assessed on pages 140-141 of the DEIR would be unlikely to prove feasible due to the current lot pattern of the area. As shown in Figure 4 and Table 1 of the DEIR, there is currently a potential infill for 105 lots on improved roads and 499 lots on unimproved roads. Only about 78 of these lots are in currently unsubdivided areas.
Without the proposed Area Plan, the unsubdivided area would be the only practical area in which to achieve more restrictive densities. The potential reduction would not be significant, and as shown in Table 1, the proposed Area Pl an would remain more restrictive than would reduced densities under the current General Plan.
The following additional text is added to page 141 of the DEIR:
"More restrictive alternative scenarios, such as a 50 percent or 75 percent reduction relative to the proposed Area Plan would result in a further relative, reduction in environmental impacts. However, the overall distribution of these fewer units would be similar to that occurring under the Area Pl an and the need for mitigation re 1 ated to specific areas of development would remain (e.g., areas of geologic hazard, visual impact, infrastructure improvements, etc.). Thus, even with a substantially reduced number of permitted units, recommended policies and mitigation measures related to environmental concerns identified in this report would remain. In addition, due to the current lotting pattern in the area it is unlikely that a significant practical reduction in potential number of units could be achieved." Cipriani Neighborhood Association Board Members
Comment #32: As professional geologists who have resided in the Cipriani Hills area of Belmont for approximately 15 years, we are aware of the hydrogeologic conditions of the San Juan Canyon area. The Geologic Hazards Analyses Report by Cotton and Assoc. (1985) and the San Juan Hills Area Plan (1986) stress the geologically unstable conditions present in the area. Our concerns relate to the basically generalized approach as stated in the Geology and Soils Section (p.48-56) and the Hydrology and Drainage Section (p.57-61) of the DEIR.
Response: The Soils and Geology, and Hydrology Drainage sections of the DEIR are intended to summarize the existing conditions and potential impacts of the proposed Area Plan and implementing ordinances. As such, these sections are neither as detailed as the background reports and information 1008
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from which they were prepared (for Geology this is primarily the 1985 Cotton Report), nor are they as site-specific as the geologic and hydrologic analyses which would be required for specific proposed developments (see Response to Comment #34, below). Specific impact analyses can only be prepared when specific developments are proposed since the impacts would vary with different projects.
Comment #33: Since the topography of the area is characterized by narrow valleys enclosed by steep slopes, investigations and proposed guidelines for slope stability are of main concern. Slope stability in the area is extremely susceptible to seismic shaking, rock type, water content of the rocks, and physical structures emplaced on the slopes. The interrelationship of these four factors in predicting slope stability for an area such as San Juan can not be over emphasized. For example, Cotton and Assoc. (1985) (p.29) properly point out the role of seismic shaking as a triggering mechanism for earthquakes. Not mentioned, however, is the complementary effect that loose materials occurring in landslide debris (as in alluvium) under saturated conditions will amplify the intensity of the shaking itself and thus further endanger the slopes and structures built upon them.
Response: In order to clarify the interrelationships between the factors influencing slope instability, the following paragraph is added as the first paragraph of page 50 in the Geology and Soils section of the DEIR:
"Slope instability, including landsliding, debris flow, mud flow, slumping, and rockfalls could all occur in the planning area. Steep slopes are present in the planning area; their stability is influenced by the rock types and bedding subsurface, surface and subsurface water content, grading and type and weight of structures built on the slopes.
In addition, because seismic shaking can serve as a triggering mechanism for slope failure, the local intensity of seismic shaking must be considered in assessing slope stability."
To further clarify this issue, the following sentence is added to the end of the second paragraph on page 50 of the DEIR:
w1t should be noted that this slope stability can vary on a micro scale dependjng on site-specific geologic conditions, and on the saturation conditions as discussed above. For example, saturated. loose materials in old Jandsl ide deposits can further amplify seismic shaking, thereby decreas;nq local slope stability.•
Comnent #34: Implementation of a well defined geologic hazard ordinance to regulate the number and design of structures for the area must include 1009
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explicit criteria to define when an engineering geologic investigation is required and most importantly, the requirements of what is to be included in the report. Soils reports on all site development and building permits should be required (p. 26, Cotton and Assoc., 1985) Since the Geologic Map submitted by Cotton and Assoc. (1985) does not reflect structure in the subsurface, areas that appear stable can in fact, be underlain by extremely geologically unstable material. Therefore, at a minimum, we encourage engineering geologic investigations for all projects involving grading in addition to those conditions stated by Cotton and Assoc. (1985). On-site inspections by the City Geologist prior to and during grading activities and at the completion of such projects definitely should be included in the ordinance.
Response: The recommendations of the Cotton report (1985) regarding required geotechnical investigations are recommended for adoption as Mitigation Measures on page 55 and on page 6 in the Summary of the DEIR. This includes the recommendation on page 26 of the Cotton report which suggests that " ... all applications for site development and building permits should be accompanied by soils reports addressing the characteristics of expansive soils."
To clarify required investigations, the following sentence is added following the first sentence of Mitigation Measure #3 on page 55 and on page 6 in the Summary of the DEIR:
"As recommended by the William Cotton Report, engineering geologic investigations should be prepared for development in the area." In addition, the following sentence is added to the end of Mitigation Measure #3 on page 55 and on page 6 in the Summary of the DEIR:
"The ordinance should include on-site inspections by a geologist before, during, and after grading activjties.11
Comment #35: Cotton and Assoc. (1985) (p. 37) stress the importance of soils and foundations engineering investigations by a registered civil engineer for hillsides steeper than 10% and mention as well the need for such studies in relatively flat terrain due to the frequent presence of expansive soils, high ground-water, loose soils, "etc." Since Belmont's policy has been to accept geotechnical reports for site development projects that were done during the dry season, little is known about actual saturated soil conditions (winter conditions) in the study area. The vast number of springs active during the winter and those active all year are not documented; therefore, in conjunction with the lack of water wells in the area, little is known about the ground-water system in the San Juan area. Perched aquifers on the 1010
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hillsides of the study area are numerous and without drilling (completed during engineering geologic investigations), soil investigations during the dry season often may prove futile for revealing geologic hazards until it is too late.
Response: The Cotton report recommendations incorporated in the mitigations of the DEIR include investigations of high ground water (Cotton, 1985, p. 37) and subsurface drainage (p. 38) for hillside areas and some local flatland areas. Seasonal variations in groundwater levels should be considered by the City in reviewing these reports. The reports should note indications of springs and seeps (i.e., riparian vegetation) that may occur even if these features are not flowing at the time of the investigation.
Comment #36: The DEIR hydrology section addresses surface water hydrology with no mention of the ground water hydrology. Hydrology can not be understood without knowledge of both aspects and it is reconmended that this section be revised to address this most important hydrogeologic input for evaluating future development in the area.
Response: The following is added as the last sentence to the first full paragraph on page 57 of the DEIR in the Hydrology section:
"There is little information available regarding subsurface hydrological features in the San Juan Hills Area. However, there are surface features, such as seeps and riparian vegetation, which are indicative of high groundwater levels."
INDIVIDUALS
P.M. Mel]iar-Smith
Comment #3 7: I wish to comment on the Envi ronmenta 1 Impact Report for the San Juan Hi 11 s Area Pl an, prepared by LSA Associates, Inc., dated April 1987. On page 126, the report states that new sewer lines would be required to be located in roadway rights-of-way for ease of maintenance. While I understand the problems currently created by sewer lines constructed through rear yards, I believe that this requirement does not adequately consider the topography of the area. In many areas, new construction will be downslope from existing construction and will be accessed by roads downslope from the existing construction. If sewer pipes are restricted to lie entirely within these roads, several new sewer pumping stations will be required. In particular, the opportunity for a gravity sewer line through the canyon to serve the Naughton/Horse Ranch/Green Court area would be precluded. 1011
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I request that the Environmental Impact Report compare the proposed policy:
o New sewer lines would be required to be located in roadway rightsof-way for ease of maintenance. with the alternative
o New domestic service sewer lines would be required to be located in roadway rights-of-way for ease of maintenance. New main sewer lines without service connections could be constructed in undeveloped dedicated access easements provided that the access easements are acceptable to the City Public Works Department.
In comparing the impacts of these alternatives, consideration should be given to:
o The number of pumping stations that may be necessary. o Ease of maintenance.
o Public health and safety {there have been major failures resulting in spillage of raw sewage at pumping stations in Belmont). o Public nuisance {e.g. odors at East Creek Drive).
o The difficulty of ensuring that private pumping stations do not eventually revert to the City for maintenance (e.g. Hastings). o The risk that unnecessary and undesirable roadway rights-of-way will be dedicated in undeveloped areas so as to accommodate sewer lines.
Response: This comment is directed to a policy of the proposed Area Plan which is reiterated on page 126 of the DEIR. Rep 1 a cement of the Pl an po 1 icy with the proposed alternative would permit sewer lines (without service connections) to be constructed in other areas. Although in certain instances alternative locations may be found acceptable to the Public Works Department, the prevalence of geologic hazards 1 n the planning area would make many locations unacceptable for sewer line connections due to environmental, public safety and maintenance constraints. This policy language change may be considered by the City in the review of the Plan.
Specific numbers and locations of sewer lines or pumping stations that would be developed under either of these policies and potential pump station 1012
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failures or nuisance odors that may occur cannot be determined in the absence of specific development plans for the area.
David Charles Steiner
Comment #38: To put things in context with my situation I will describe it. Upper Lock currently has water, sewer, gas, and electricity at the property's edge. There are homes up and down the street from my lot. The slope is moderate {39% average slope and even less at the building site} from the estimation of an architect who is constantly dealing with foundations, soils and geologic reports, and slope drainage. The only reason stated for not allowing a building permit when my application was submitted in December of 1985 was that the road wasn't paved. Numerous homes on the Peninsula are doing fine without paved roads.
The report had no analysis of my type of situation. The report had no explanation of why my lots should be required to help with the mitigation measures proposed for a sliding parcel nowhere near my property and why other land in Belmont should not be required to help with the mitigating measures proposed.